ETAS_MCQ_01 structures of skin
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ETAS_MCQ_01 structures of skin ETAS_MCQ_01 structures of skin Document Transcript

  • Structures of skin1) Dermal dendrocytesA. are the primary cell found in a glomangioma.B. actively synthesize and release IgG.C. are responsible for immediate-type hypersensitivity reactions.D. present antigen to naïve T cells in the lymph node. Correct ChoiceE. are the primary cell found in an angiosarcoma.A dermal dendrocyte is a mononuclear phagocytic cell that is a type of antigen presenting cell. Itis derived from the bone marrow and found both in the papillary and upper reticular dermis. Thiscell is highly phagocytic and synonymous with the melanophage that has ingested pigment.Dermal dendrocytes are likely very important to the afferent limb of the immune response.2) What is the major component of the anchoring fibril?A. Type III CollagenB. Type I CollagenC. Type VII CollagenCorrect ChoiceD. Type IV CollagenE. Laminin 5Anchoring fibrils are made of Type VII collegen. Anchoring plaques are made of Type IV collagen,and interact with a network of Type I And Type III collagen fibers in the dermis3) What is the most abundant collagen found on fetal skin?A. Type III CollagenCorrect ChoiceB. Type II CollagenC. Type IV CollagenD. Type VII CollagenE. Type I CollagenType III collagen is found in the fetal skin. It is also present in the gastrointestinal tract, bloodvessels, and the basement membrane. A defect in this collagen results in the Ehlers-Danlos,vascular type.4) Mutations in which of the following proteins results in epidermolysis bullosa simplex associatedwith muscular dystrophyA. Laminin 5B. UnceinC. collagen type IVD. Plectin Correct ChoiceE. a6b4 integrin 1
  • Anchoring filaments exist within the lamina lucida. They are primarily comprised of laminin 5 andBP180. Laminin 5 is a cross-shaped assembly of 3 classes of polypeptides, a, b, g. Theanchoring filaments function as a structural network to which other proteins attach, and theyfunction as signaling molecules that transmit morphogenetic information to transmembraneproteins of the basal cell layer (such as the integrins). Laminin 5 is also called epiligrin and bindsto the a6b4 integrin at the hemidesmosome.5) The finding on DIF that reflects binding of the Ro and La antigens in subacute cutaneous lupuserythematosus is:A. Immune deposits along the DE junctionB. Granular deposits along the basement membraneC. Cytoid bodiesD. Granular fluorescence throughout the cytoplasm and nucleus of basal keratinocytesCorrectChoiceE. A "chicken-wire" pattern within the epidermisGranular fluorescence throughout the cytoplasm and nucleus of basal keratinocytes reflect thebinding of Ro and La antigens and is unique to SCLE. Cytoid bodies and Immune deposits alongdermal-epidermal junction are seen in both DLE and SCLE. Granular deposits along thebasement membrane are seen in dermatitis herpetiformis and a chicken-wire pattern of staining isseen in pemphigus vulgaris.6) Which of the following markers are specific and reliable for Merkel cells?A. CD34B. CK20Correct ChoiceC. CD20D. HMB-45E. CD3Cytokeratin (CK) 20 is a reliable marker for Merkel cells. CD20 is a marker for B-cells and CD3 isa T-cell marker. HMB-45 is used in staining for immature melanosomes and is reactive inmelanoma. CD34 is used to stain dermatofibrosarcoma protuberans.7) Apocrine glands are found in all of the following areas of the body except:A. AxillaeB. PerineumC. BreastsD. EyelidE. Palms Correct ChoiceApocrine glands operate by decapitation secretion and are activated by epinephrine andnorepinephrine. They are located in a few distinct areas of the body, which include axillae,anogenital region, Moll’s glands of the eyelids, mammary glands of the breast and theceruminous glands of the external auditory canal.8) Which mechanoreceptor found in hair bearing areas sense deep touch and vibration? 2
  • A. Krase end-bulbB. Vater-Pacini corpuscleCorrect ChoiceC. Merkel cellD. Meissner corpuscleE. Free nerve endingVater-Pacini corpuscles sense deep touch and vibration. Merkel cells are slow adapting type Imechanoreceptors found among basal keratinocytes. Meissner corpuscles are found in thedermal papilla, especially in the palms and soles. Krase end-bulbs are mucocutaneous end-organs found on the glans penis, prepuce, clitoris, labia minora, and vermillion border of the lip9) Glomus cells areA. monocytes.B. vascular smooth muscle cells. Correct ChoiceC. modified fibroblasts.D. neuronal cells.E. modified skeletal muscle cells.Glomus cells are derived from Suquet-Hoyer canals. They are vascular smooth muscle cells thatallow the rapid shunting of blood from the arterioral to venular system, bypassing the capillaries.This process occurs primarily on the palms and soles.10) Which protein is the largest component of the cornified cell envelope?A. KeratinB. ProfilaggrinC. InvolucrinD. LoricrinCorrect ChoiceE. CeramideThe cornified cell envelope is a durable, protein-lipid polymer that eventually acts as amechanical and chemical barrier on the exterior of cornified cells. In the upper spinous layer,keratohyaline granules release profilagrin and loricrin. Profilaggrin is cleaved to filaggrin andsubsequently aggregates keratin filaments. Loricrin is the major protein component of thecornified cell envelope and is bound to the cell membrane by transglutaminases (in addition toother structural proteins like involucrin, keratins, elafin, cystatin A and desmosomal peptides).This forms the highly insoluble proteinaceous component of the cornified cell envelope.11) Embryologically, epidermal stratification occurs at approximately what estimated gestationalage?A. 20 weeksB. 16 weeksC. 8 weeksCorrect ChoiceD. 12 weeks 3
  • E. 4 weeksEpidermal stratification begins at about 8 weeks estimated gestational age and is completed bythe 2nd trimester. Epideral stratification occurs when an intermediate layer develops betweenthe epidermal basal cells and the overlying layer of periderm cells. The periderm is an embryonicstructure that covers the primitive epidermis until keratinization begins, at which point theperiderm sloughs off and contributes to the protective covering of the newborn, the vernixcaseosa. This intermediate layer is highly proliferative, such that by 24-25 weeks estimatedgestaional age, the epidermis consists of 4 or 5 layers, in addition to the degenerating periderm12) A specific marker of Merkel cells isA. EnvoplakinB. Cytokeratin 10C. LoricrinD. Cytokeratin 20 Correct ChoiceE. Cytokeratin 15Cytokeratin 20 is a specific marker for the Merkel cell. Merkel cells are mechanoreceptors locatedat body sites requiring high tactile sensitivity. Keratinocyte deformation results in a secretion ofchemokines by Merkel cells, which make synaptic connection with neurons.13) On electron microscopy, which cell demonstrates cytoplasmic projections and secretorygranules?A. macrophageB. Langerhans cellC. keratinocyteD. mast cellCorrect ChoiceE. melanocyteElectron microscopy of mast cells demonstrates large long villi at the periphery and round or ovalsecretory granules. Langerhans cells show a folded nucleus and rarely phagocytizedmelanosomes on electron microscopy. Their characteristic feature is the presence of Birbeckgranules whose disk shape with one or two vesicles at either end represents a tennis raquet.Examination of melanocytes shows an absence of tonofilaments or desmosomes withcharacteristic melanosomes in various stages of formation. Macrophages often containphagocytized material within phagosomes.(Levers Histopathology of the Skin 8th ed 1997 p.32.)14) Upon presentation of an antigen in the skin surface, a hapten forms. The first cell to take upthe hapten isA. Mast cellB. T cellsCorrect ChoiceC. B cellsD. keratinocytes 4
  • E. Langerhans cellsMost of the contact allergens are low-molecular weight chemicals, which after penetrating into theskin, have to couple with host proteins to be able to act as full antigens. These are calledhaptens. Upon epicutaneous application to a naive host, Langerhans cells take up the hapten,process it and migrate towards the regional lymph nodes, where the anitgen is presented to thenaive T cells15) Elastic fibers contain the specific amino acidsA. Alanine and phenylalanineB. Glycine and prolineC. Desmosine and isodesmosine Correct ChoiceD. Leucine and isoleucineE. Lysine and prolineDesmosine and isodesmosine are the typical amino acids of elastic fibers. Elastic fibers arecomprised of elastin that is wrapped by fibrillin microfibrils. Elastic fibers form a complexmeshwork extending from the lamina densa of the dermo-epidermo junction through the dermis.Elastic fibers return the skin to a normal shape after being stretched.16) Apocrine chromhidrosis results in from which of the following contents of apocrine sweat?A. squaleneB. cholesterolC. ammoniaD. lipofuschinCorrect ChoiceE. fatty acidsChromhidrosis refers to the secretion of pigmented sweat, most commonly yellow, green or black.It reflects the rich lipofuschin content of apocrine sweat. Extrinsic apocrine chromhidrosis resultsfrom staining of sweat and garments by chromogenic bacteria, such as Corynebacterium spp.17) The major component of the anchoring filaments isA. UnceinB. PlectinC. Laminin 5 Correct ChoiceD. a6b4 integrinE. Collagen type IVAnchoring filaments exist within the lamina lucida. They are primarily comprised of laminin 5 andBP180. Laminin 5 is a cross-shaped assembly of 3 classes of polypeptides, a, b, g. Theanchoring filaments function as a structural network to which other proteins attach, and theyfunction as signaling molecules that transmit morphogenetic information to transmembraneproteins of the basal cell layer (such as the integrins). Laminin 5 is also called epiligrin and bindsto the a6b4 integrin at the hemidesmosome.18) Which of the following make up the major protein of the cornified cell envelope? 5
  • A. FilaggrinB. LoricrinCorrect ChoiceC. InvolucrinD. Laminin VE. EnvoplakinLoricrin is the major protein component of the cornified cell envelope (CE). Involucrin is cross-linked by transglutaminae in the granular layer to form an insoluble cell boundary. Envoplakinmay link the CE to desmosomes and to kertin filaments. Filaggrin is thought to promoteaggregation and disulfide bonding of keratin filaments in CE. It is degraded into urocanic acid andpyrrolidone carboxylic acid. Both of which hydrate the stratum corneum and block UV radiation.Laminin V is found in the basement membrane and is not involved in the formation of thecornified cell envelope.19) Tissue contraction beginsA. after the 3rd month of wound healing.B. after the first month of wound healing.C. after the 9th month of wound healing.D. at 3rd day of wound healing.E. during the 2nd week of wound healing. Correct ChoiceSee discussion of wound healing from questions 29 through 33.20) Telogen effluviumA. results from sudden illness or surgery. Correct ChoiceB. involves a diffuse alopecia affecting more than 50% of the scalp.C. is an inflammatory alopecia devoid of scarring.D. often results from antimetabolites used during cancer chemotherapy.E. is a patchy alopecia affecting less than 50% of the scalp.Telogen effluvium is an excessive loss of club hairs from the normal resting follicles of the scalp.The follicle is pushed from anagen to catagen to telogen. There is no inflammatory processinvolved. Causes of telogen effluvium are illness, surgery, parturition, fever, drugs, traction,starvation, and hypervitaminosis A. Usually, the hair loss only involves less than 50% of thescalp. There is no specific therapy, and most cases are self-resolving within months.21) Cutaneous warts in renal transplant recipients show increased expression of which keratin?A. K2B. K16C. K5D. K9E. K13Correct Choice 6
  • Keratins are divided into acidic (type I) and basic (type II) subtypes. Keratin 13 is a type I keratinwhich is expressed suprabasally in adult epithelia and is associated with terminal differentiation.Renal transplant recipients have an increased risk of developing skin cancers and multiple warts.Factors contributing to this increased risk include human papillomavirus infection,immunosuppressive therapy, and exposure to ultraviolet radiation. Increased expression of K13has been demonstrated in high-risk papillomas in this patient population.(Blokx W. Arch Dermatol 2002; 138:61-6522) Which of the following glands is not under neural control?A. Eccrine glandsB. Apocrine glandsC. Salivary glandsD. Sebaceous glandsCorrect ChoiceE. Ceruminous glandsSebum is secreted continuously on the skin under hormonal glands. It contains squalene,cholesterol, cholesterol esters, wax, and triglycerides23) The major protein component of the cornified envelope isA. PlectinB. EnvoplakinC. Loricrin Correct ChoiceD. TransglutaminaseE. DesmoplakinLoricrin is the major component of the cornified envelope (CE). The proteins of the CE aresynthesized in the spinous and granular layers.The CE is primarily a protein/lipid polymer formed within the differentiating layer of keratinocytes.The CE eventually exists outside of the cornified cells after the granular cell undergoes aprogrammed destruction (apoptosis). Self-destructing granular cells are called transition cells.24) Acid keratins (K10-20) are expressed on which of the following chromosomes?A. 12B. 17Correct ChoiceC. 18D. 19E. 10Acid keratins are expressed on chromosome 17 and basic keratins on chromosome 12. The otherlisted options do not have active keratin functions.25) Tyrosinase is the enzyme that catalyzes the conversion fo tyrosine to DOPA and DOPA toDOPAquinone. The enzyme contains which of the following ions? 7
  • A. IronB. MagnesiumC. CopperCorrect ChoiceD. SeleniumE. ZincTyrosinase is a copper containing enzyme that is responsible for the conversion fo tyrosine toDOPA and DOPA to DOPAquinone.26) Choose the correct answer regarding melanin and skin colorA. Facultative skin color is the amount of cutaneous melanin pigment generated according tocellular geneticsB. In black and brown skin the melanosomes are smaller in diameter and lengthC. The number of melanocytes increases with one exposure to UVA/visible lightD. In white skin the melanosomes form groups within the secondary lysosomes Correct ChoiceE. Eumelanin produces a yellow chromophoreMelanocytes of dark skin synthesize melanosomes larger than those produced in light skin (thus(A) is incorrect). The number of melanocytes in the epidermis is the same, regardless of thepersons race or color: it is the number and size of the melanosomes or pigment granules,continuously synthesized by these melanocytes, that determine differences in skin color (thus (E)& (B) are incorrect). The size of th melanosome is the principle factor in determining how themelanosomes will be distributed within the keratinocytes. The larger the melanosomes of darkskin are individually dispersed within the cytoplasm of keratinocytes: smaller melanosomes oflight skin are packaged in membrane-bound complexes within keratinocytes (thus (C) is correct).Eumelanin is in dark oval melanosomes found in black hair (thus (D) is incorrect27) Each of the following is true about melanosomes except:A. Are transferred to keratinocytes via phagocytosisB. Tyrosinase activity decreases as melanosomoes matureC. Most characteristic organelle of the melanocyteD. Are singly dispersed in the basal layer in white skinCorrect ChoiceE. Are larger in size in black skin compared to white skinSeveral differences exist that may explain the heterogeneity of skin color. The number ofmelanocytes are the same; however, there are several differences in the melanosomes.Differences in skin color can be attributed to five factors. In racially heavily pigmented skin, (1)there is greater production of melanosomes in melanocytes, (2) individual melanosomes show ahigher degree of melanization, (3) melanosomes are larger, (4) the melanosomes are dispersedto a greater degree in the keratinocytes, and (5) there is a slower rate of degradation.28) Which cytokeratin would you expect to be preferentially expressed in the keratinocytes of apsoriatic plaqueA. K5B. K1C. K12 8
  • D. K15E. K16Correct ChoiceK16 and K6 act as markers for hyperproliferative keratinocytes. They are found in skin diseasesuch as psoriasis, warts, actinic keratoses, and SCCs29) All of the following are true regarding the formation of hair except:A. The hair matrix becomes the hair and the inner root sheathB. The outer root sheath is a downward extension of the epidermisC. Huxley’s layer contains melaninCorrect ChoiceD. Henle’s layer is outside of Huxley’s layerE. The inner root sheath keratinizes by means of trichohyalin granulesThe inner root sheath is composed of three layers, which are the inner root sheath cuticle, Huxleylayer, Henle layer. None of these layers contain melanin. All three layer keratinize bytrichohyaline granules and disintegrate when they reach the isthmus of the hair follicle.30) The hair follicle is the site of production or conversion of which of the following hormones?A. adrenocorticotropin hormone (ACTH)B. prolactinC. dihydrotestosterone (DHT)D. alpha-melanocyte stimulating hormone (MSH)E. All the options are correctCorrect ChoiceThe hair follicle converts gonadal or aderenal testosterone to dihydrotestosterone locally via 5-alpha reductase. It also cleaves proopiomelanocortin to ACTH, alpha-MSH, and B-endorphin viaprohormone convertase. It also secretes corticotropin releasing hormone (CRH) as well asprolactin.31) Sebaceous glands are located in each of the following locations except:A. Buccal mucosaB. EyelidsC. NippleD. Palms Correct ChoiceE. Labia minoraSebaceous glands secrete their contents in a holocrine fashion and are primarily under theinfluence of androgens. They secrete triglycerides, phospholipids, esterified cholesterol, waxesbut not free cholesterol. They may be found in association with hair follicles or in some areas ofmodified skin such as the nipple/areola, labia minora, prepuce, vermilion border, and eyelids.32) Which keratins are upregulated in hyperproliferative disease such as psoriasis?A. Keratins 5 and 14B. Keratins 2e and 10 9
  • C. Keratins 6 and 16Correct ChoiceD. Keratins 8 and 18E. Keratins 1 and 10Keratins 6 and 16 are upregulated in hyperproliferative keratinocytes, outer root sheath, and oralepithelium. A defect in these keratins may result in pachyonychia congenita.33) Total epidermal renewal time (including dividing, movement through the granular layer, andbeing shed from the stratum corneum) is approximatelyA. 9-25 daysB. 29-35 daysC. 1-4 daysD. 59-75 daysCorrect ChoiceE. 5-7 daysA cell takes about 19 days to divide, 26-42 days to move up through the granular layer, and 14days to shed from the stratum corneum. Therefore the total epidermal renewal time is about59-75 days34) Markers for epidermal proliferation seen in psoriasis and actinic keratoses areA. K1/K9B. K2/K9C. K5/K14D. K6/K16Correct ChoiceE. K6/K16Plectin is found in the basement membrane zone and functions to link intermediate filaments tothe plasma membrane. Mutations in plectin result in epidermolysis bullosa associated withmuscular dystrophy. Plectin is a member of the plakin family. Other members of this family areenvoplakin, periplakin, desmoplakin, and BP230 (BPAg1).35) Which of the following keratins would most likely be expressed in the nail bed?A. K6b/17Correct ChoiceB. K6a/16C. K1/9D. K2e/10E. K4/13Keratins 6b & 17 are expressed in the nail bed. K6a/16 is expressed in the outer root sheath andin hyperproliferative keratinocytes, 1/9 in palmoplantar suprabasalar keratinocytes, 2e/10 in theupper spinous and granular cell layers, and 4/13 are expressed in mucosal epithelium.36) What is the major function of urocanic acid? 10
  • A. primarily a UVA filterCorrect ChoiceB. primarily a UVB filterC. aids in protecting the skin from dermatophytesD. helps degrade free fatty acidsE. bacteriocidal acid produced by stratum corneumUrocanic acid a by product of filaggrin degradation and has a peak absorbtion of 345 nm. Itserves as a major UVA filter.37) Hair grows atA. 10 mm/dayB. 0.004 mm/dayC. 0.04 mm/dayD. 4 mm/dayE. 0.4 mm/dayCorrect ChoiceHair grows at an average of 0.4 mm/day. The other options are incorrect.38) Which of the following dermal cells always express CD11c and CD6?A. Mononuclear phagocytic cellsCorrect ChoiceB. Glomus cellsC. Dermal dendrocytesD. FibroblastsE. Mast cellsThe mononuclear phagocytic cell includes monocytes, macrophages and dermal dendrocytes. Allphagocytic skin macrophages express CD11c and CD6. Fibroblasts do not produce a CD marker.Mast cells are derived from bone marrow-residing CD34+ stem cells. They do not produce CD11cor CD6. Dermal dendrocytes do not express these marker either.39) Which of the following domains is targeted by the autoantibodies in bullous pemphigoid?A. NC16A of BP230B. alpha-6 integrinC. NC16A of BP180Correct ChoiceD. Laminin 5E. PlectinThe NC16A domain of BP180 is the target of autoantibodies in bullous pemphigoid. It interactswith alpha-6 integrin extracellularly40) Which of the following statements is true about eccrine glands?A. postganglionic sympathetic fibers with acetylcholine as the principal neurotransmitterCorrect 11
  • ChoiceB. postganglionic sympathetic fibers with both norepinephrine and acetylcholine as the principalneurotransmittersC. postganglionic parasympathetic fibers with norepinephrine as the principal neurotransmitterD. postganglionic parasympathetic fibers with acetylcholine as the principal neurotransmitterE. postganglionic sympathetic fibers with norepinephrine as the principal neurotransmitterEccrine glands are innervated by postganglionic sympathetic fibers with acetylcholine as theprincipal neurotransmitter. This explains why medications associated with anticholinergic sideeffects may be associated with hypohidrosis.41) Eccrine glands are found in all the following areas of the body except:A. Labia minoraCorrect ChoiceB. ScalpC. AxillaeD. Cutaneous lipE. PalmsEccrine glands are sweat glands enervated by cholinergic sympathetic nerves mediated byacetylcholine. They absent on modified skin which lacks appendages like the vermillion border,nail beds, glans penis, inner aspect of the prepuce and the labia minora.42) Which of the following statements about the direct immunofluorescence pattern in lichenplanus is correct?A. Deposition of IgG is within cytoid bodies in the superficial dermisB. Deposition of fibrinogen is within cytoid bodies in the deep dermisC. The DEJ deposition is granularCorrect ChoiceD. There is prominent deposition of IgM within the spinous layer of the epidermis.E. The DIF is negative in the vast majority of casesThe DEJ deposition is granular. The DIF is positive in the vast majority of cases. Deposition ofIgM and fibrinogen is within cytoid bodies in the superficial dermis. There is no deposition of IgMwithin the spinous layer of the epidermis.43) Which of the following locations has eccrine glands?A. under nailsB. labia majoraCorrect ChoiceC. penisD. ear canalE. labia minoraEccrine glands are enervated by cholinergic sympathetic nerves, mediated by acetycholine. Theyare absent on modified skin that lack appendages such as the vermillion border, nail bed, labiaminora, glans penis and ear canal. They are present of the labia majora. 12
  • 44) of linking proteins?A. desmocollinB. plakoglobinCorrect ChoiceC. E-cadherinD. periplakinE. envoplakinPlakoglobin is an example of an armadillo protein, which links the cytoskeleton associated linkingproteins (such as plakins in the case of intermediate filaments and alpha-catenin in the case ofactin) to the transmembrane adhesion molecules, termed cadherins. E-cadherin and desmocollinare examples of cadherins. Periplakin and envoplakin are examples of plakin linking proteins.45) Hair follicle development in the human embryo begins duringA. Within 2 weeks of fertiizationB. 3rd trimesterC. At the blastocoele stageD. 2nd trimesterE. 1st trimesterCorrect ChoiceHair follicles begin in the third month of fetal life as a downgrowth of cells from the epidermis (3rdmonth=12th week=1st trimester)46) Which of the following cells are required for wound healing?A. LymphocyteB. EosinophilC. MacrophageCorrect ChoiceD. NeutrophilE. Langerhans cellThe macrophage is required for wound healing. The macrophages debride tissue, secretecollagenase and stimulate expression of FGF, IL-1, TGF-beta, PDGF and TGF-alpha thusfacilitating transition from inflammation to repair.47) Anagen effluviumA. All of these options are correctCorrect ChoiceB. Stimulus induces the abrupt cessation of mitotic activity in the rapidly dividing hair matrix cellsC. Frequently seen sollowing administration of cancer chemotherapeutic agentsD. Occurs within days to weeks of exposureE. Is entirely reversibleAll of the above statements regarding anagen effluvium are correct. Frequent causes includeantimetabolites, alkylating agents, mitotic inhibitors, thallium, boron. 13
  • 48) What component is the major barrier in the stratum corneum?A. TriglyceridesB. SqualeneC. SebumD. CollagenE. CeramideCorrect ChoiceThe major component of lamellar granules of the keratinocytes is ceramide. These play a majorrole in the barrier function of the skin.49) Meibomian glands areA. apocrine glands found on the eylelids.B. eccrine glands localized to the vermillion border of the lips.C. sebaceous glands found on the areola of the breast.D. apocrine glands found in the anogenital regions.E. sebaceous glands found on the eyelids. Correct ChoiceSebaceous glands enlarge at puberty in response to increased levels of androgens. They areholocrine glands. Meibomian glands are modified sebaceous glands found in the eyelids. Freesebaceous glands not associated with hairs are found in the nipple and areola and are calledMontgomery’s tubercles. Fordyce’s condition involves free sebaceous glands on the vermillionborder of the lips and on the buccal mucosa. Sebaceous glands are found everywhere on theskin except the palms and soles.50) A salt split skin DIF is performed on a biopsy taken adjacent to the skin lesions shown. Wherewould you expect staining to be seen?A. Dermal sideB. Epidermal and Dermal sides equallyC. In the anchoring plaquesD. In the lamina densaE. Epidermal sideCorrect ChoiceThe image shown is bullous pemphigoid. On salt split skin DIF exams, deposits are seen on theepidermal side of the split. If dermal deposits are seen, epidermolysis bullosa acquisita or anti-epiligrin pemphigoid are potential diagnoses51) Pick the correctly paired keratin with its structureA. K3/K12 - esophagusB. K16/K6 - palms and solesCorrect ChoiceC. K5/K14 - suprabasal cellsD. K4/K13 - corneaE. K1/K10 - basal cells 14
  • Keratin 1 and 10 are found in the stratum spinosum (thus (A) is incorrect). K5 and K14 are foundin the basal layer (thus (D) is incorrect). K3 and K12 are found in the suprabasilar cells of thecornea (thus (B) is incorrect). K4 and K13 are found in the non-cornifying cells of stratifiedmucosa (thus (C) is incorrect). K16 and K6 are found in the palms and soles (thus (E) is correct).52) Defects in what kind of structural protein lead to pyloric atresia associated with junctionalepidermolysis bullosa:A. Integrin Correct ChoiceB. LoricrinC. CollagenD. ElastinE. PlectinJunctional epidermolysis bullosa with pyloric atresia involves a defect in the b4 subunit of thea6b4 integrin. The expression of this protein is limited to the basal layer of the epidermis. Thisintegrin is a transmembrane protein that coordinates a link between the intermediate filaments(keratins) and the extracellular matrix of the basement membrane. The b4 domain mediates aninteraction with both plectin and BP180; its absence prevents hemidesmosomal assembly.53) Moving from internally to externally choose the correct description of the hair follicle:A. Henle’s layer _ Huxley’s layer _ inner root sheath cuticle _ hair shaft cuticle _ cortex _ medullaB. inner root sheath cuticle _ outer root sheath cuticle _ hair shaft cuticle _ cortex _ Huxley’s layer_ Henle’s layerC. inner root sheath cuticle _ Huxley’s layer _ Henle’s layer _ medulla _ cortex _ hair shaft cuticleD. hair shaft cuticle _ cortex _ medulla _ Henle’s layer _ Huxley’s layer _ inner root sheath cuticleE. medulla _ cortex _ hair shaft cuticle _ inner root sheath cuticle _ Huxleys layer _ Henles layerCorrect Choice(As described in correct choice)54) Homocystinuria has abnormal crosslinking of collagen because of a mutation in:A. cystathione synthaseCorrect ChoiceB. lysyl oxidaseC. lysyl hydroxylaseD. type I collagen N-peptidase geneE. Tenascin XHomocystinuria is caused by a mutation in cystathione synthase. The main skin findings are amalar flush, livedo reticularis and leg ulcerations. A characteristic eye finding is the downwarddisplacement of the lens. The other options are involved in abnormalities associated with Ehlers-Danlos syndrome. Lysyl hydroxylase is deficient in Kyphoscoliosis type of EDS. Tenascin X isinvolves in ~3% of Classical type EDS cases. Dermatosparaxis type EDS has recessivemutations in the type I collagen N-peptidase gene.55) At what estimated gestational age are all layers of the keratinized epidermis identifiable? 15
  • A. 20 weeksB. 12 weeksC. 16 weeksD. 24 weeksCorrect ChoiceE. 8 weeksAt 24 weeks, all the layers of the mature epidermis can be identified, and the epidermis iskeratinized56) Which of the following is NOT characterized by IgG and/or C3 at the basement membranezone?A. Mucosal pemphigoidB. Pemphigus vulgarisCorrect ChoiceC. Bullous pemphigoidD. Pemphigoid gestationisE. Epidermolysis bullosa acquisitaAll of the listed conditions except pemphigus vulgaris have IgG and/or C3 deposits at thebasement membrane zone. Pemphigus vulgaris is characterized by IgG deposition in theintercellular space of the epidermis.57) Keratinocytes have been shown to secrete all of the following cytokines except:A. IL-1B. IL-6C. TNF-alphaD. IL-8E. IL-2Correct ChoiceKeratinocytes have been shown to secrete all of the above cytokines, except IL-2, IL-4, and IFN-gamma58) Which one of the following is responsible for maintaining a barrier to water loss in the stratumcorneum?A. involucrinB. transglutaminaseC. loricrinD. odland bodiesCorrect ChoiceE. filaggrinOdland bodies, also known as lamellar granules, keratinosomes, and membrane-coatinggranules, are small organelles that are discharged from granular cells into the intracellular spaceof the granular layer of the epidermis. These bodies have two known functions: they mediatestratum corneum cell cohesion and they form a barrier to water loss. Odland bodies are round tooval, measure approximately 300 to 500 nm in diameter, and possess a trilaminar membrane and 16
  • a laminated interior. They contain neutral sugars linked to lipids and/or proteins, hydrolyticenzymes, and free sterols.Filaggrin is a breakdown product of filaggrin precursor, a component of keratohyaline granules,which aggregates with keratin filaments and acts as a "glue" for keratin filaments. Involucrin is acysteine-rich protein synthesized in the cytoplasm of spinous cells. The enzyme,transglutaminase, cross-links involucrin in the granular layer forming an insoluble cell boundarythat is resistant to denaturing and reducing chemicals. Loricrin, is a highly insoluble sulfur- andglycine/serine-rich protein, which is the major protein comprising the cornified cell envelope.(Levers Histopathology of the Skin. 8th ed 1997 p11)(Fitzpatricks Dermatology in General Medicine. 5th ed 1999, p 136-138)59) Which signaling molecule mediates the transition of hair cycling from telogen to anagenphase?A. Fgf5B. Foxn1C. 5a-reductaseD. DihydotestosteroneE. Sonic hedgehogCorrect ChoiceSonic hedgehog (Shh), a signaling molecule secreted by ectodermal cells of the developing hairfollicle, appears to be critical in mediating the transition from telogen to anagen during postnatalhair cycling60) Apocrine glandsA. demonstrate decapitation secretion. Correct ChoiceB. are fully functional at birth.C. are thermoregulatory.D. are diffusely distributed on the body.E. demonstrate holocrine secretion.Apocrine glands show decapitation secretion. Like eccrine glands, apocrine glands are composedof three segments, the intraepidermal duct, the intradermal duct, and the secretory portion. Theduct of the apocrine gland usually leads to a pilosebaceous follicle above the entrance of thesebaceous duct. Apocrine glands are found in the axillae, anogenital region, external ear canal(ceruminous glands), in the eyelids (Moll’s glands), and in the breast (mammary glands).Apocrine glans are functional only at puberty. Their initial secretion is odorless. Hidradenitissuppuritiva is a disease involving apocrine glands.61) Which element is necessary for function of matrix metalloproteinases?A. ironB. zincCorrect ChoiceC. magnesiumD. nitrogenE. manganese 17
  • Matrix metalloproteinases are required for normal tissue architecture and normal turnover of theextracellular matric. All of them have zinc at the active site and require octahedral binding ofcalcium ions to maintain structural integrity.62) The strength of a scar:A. None of these options are correctB. All of these options are correctCorrect ChoiceC. Is 20% at 3 weeksD. Is 5% at 1 weekE. Is 70% at 1 yearA scar has 5% strength at 1 week, 20% at 3 weeks and 70% at 1 year. It will never recoverstrength to the level of pre-injury.63) Which hormone is homologous to alpha-MSH (melanocyte stimulating hormone)?A. insulinB. thyroid stimulating hormoneC. prolactinD. adrenocorticotropic hormoneCorrect ChoiceE. human growth factorBoth alpha-MSH and ACTH are cleavage products of proopiomelanocortin (POMC).64) The microflora of pilosebaceous unit consist of which of the following:A. Staphylococcus aureusB. Pseudomonas aeruginosaC. Pityrosporum ovaleCorrect ChoiceD. Escherichia coliE. Corynebacterium diphtheriaeAll the above bacteria and fungi are found within sebaceous glands; the Malasssezia spp. and P.ovale are found within the acroinfundibulum, S. epidermidis is found within the midinfundibulum,and Propionibacterium spp. deep within the follicle.65) Human sebum is distinguished from lipids of internal organs by the presence of:A. SqualeneB. Wax estersCorrect ChoiceC. GlyceridesD. CholestrolE. Cholestrol estersAs human sebum exits the sebaceous gland, its major constituents are squalene, cholesterol,cholesterol esters, triglycerides, and wax esters. With passage through the hair follicle, 18
  • triyglycerides in the sebum become hydrolyzed by bacterial enzymes, so that by the time thesebum reaches the skin surface, it contains free fatty acids, mono- and diglycerides in addition tothe original components. Human sebum is distinguished by the presence of wax esters andsqualene. The lipids of human internal organs contain no wax esters and little squalene. Thesqualene that is produced in internal organs is quickly converted to lanosterol and then tocholesterol, so it does not remain in its original form. Human sebaceous glands do not convertsqualene to sterols.(Fitzpatricks Dermatology in General Medicine. 5th ed 1999, p [ ] Chapter 1066) In X-linked ichthyosis, steroid sulfatase is missing from:A. peroxisomal granulesB. lamellar granulesCorrect ChoiceC. basal keratinocytesD. dermal fibroblastsE. Odland bodiesSteroid sulfatase is missing from lamellar granules in the stratum corneum in X-linked ichthyosis.There is an increase in cholesterol sulfate and decreases in cholesterol levels. This may be themechanism for the retention hyperkeratosis seen in this condition.67) Each of the following is true about the basement membrane zone except:A. Contains laminin 1 and laminin 5B. Anchoring filaments attach the basal cell membrane to the lamin lucidaCorrect ChoiceC. Can be visualized on light microscopy with PAS stainingD. Lamina densa is composed of type IV collagenE. Anchoring fibrils are composed of type VII collagenThe basement membrane zone is seen on staining with PAS stain. It appears as a homogenousband approximately 1 micron thick at the dermo-epidermal junction. The hemidesmosomalcomplex and basement membrane zone play an integral role in maintaining cellular adhesion.Anchoring filaments (primarily composed of laminin 5 and BPAG2) attach the basal cellmembrane to the lamina densa NOT lamina lucida.68) Dystrophic epidermolysis bullosa results from mutations inA. collagen type III.B. collagen type II.C. collagen type I.D. collagen type VII. Correct ChoiceE. collagen type V.See discussion from question 1269) Which of the following medications is concentrated in the eccrine glands? 19
  • A. all of the answers are correctCorrect ChoiceB. cytarabineC. cephalexinD. cyclophosphamideE. ciprofloxacinThe above listed drugs, as well as beta-lactam antibiotics, antifungals such as ketoconazole andgriseofulvin, are known to be secreted into eccrine sweat ducts. This feature may explain thedevelopment of neutrophilic eccrine hidradenitis and eccrine squamous syringometaplasia in thecontext of chemotherapy.70) What is the average duration of the telogen cycle in terminal scalp hair?A. 9 monthsB. 6 monthsC. 2-3 weeksD. 2-6 yearsE. 3 monthsCorrect ChoiceThe average duration of the telogen phase of the hair cycle is 3 months; this feature explains whytelogen effluvium is typically observed 3 months following a traumatic event or serious illness.The average duration of the anagen phase of the hair cycle is 2-6 years, whereas that of thecatagen cycle is 2-3 weeks.71) At any one time, the approximate proportion of hair follicles in anagen isA. 40%B. 85% Correct ChoiceC. 95%D. 60%E. 15%Most hair follicles are in anagen, and thus most hair follicles involve growing hair. The longer ahair follicle is anagen, the longer the hair can grow in length. Hairs of the scalp growapproximately 0.4 mm per day, and thus the date of your next hair cut can be accuratelycalculated.72) Desmosine and isodesmosine are typical amino acids found in:A. Collagen fibersB. Anchoring plaquesC. Anchoring fibrilD. Elastic fibersCorrect ChoiceE. Heparan sulfateDesmosine and isodesmosine are typical amino acids found in elastic fibers. They crosslinkfibrillin. Anchoring fibrils are composed of collagen VII and collagen fibers and have the most 20
  • typical amino acids of proline and hydroxyproline. Heparan sulfate do not typically contain theseamino acids.73) What is the location of the unbound corticosteroid receptor?A. mitochondriaB. golgi apparatusC. nucleusD. plasma membraneE. cytoplasmCorrect ChoiceBoth androgen and corticosteroid receptors localize to the cytoplasm. Estrogen receptors arefound in the nucleus. Progesterone receptors are distributed in both the nucleus and thecytoplasm74) The epidermis is comprised of what type of cells?A. Keratinocytes, Melanocytes, Neutrophils, Langerhan cellsB. Keratinocytes, Endothelial cells, Merkel cells, Goblet cellsC. Keratinocytes, Melanocytes, Merkel cells, Goblet cellsD. Keratinocytes, Endothelial cells, Merkel cells, Langerhan cellsE. Keratinocytes, Melanocytes, Merkel cells, Langerhan cellsCorrect ChoiceThe adult epidermis is composed of three basic cell types: Keratinocytes, melanocytes, andLangerhans cells. An additional cell, the Merkel cell, can be found in the basal layer of the palmsand soles, the oral and genital mucosa, the nail bed, and the follicular infundibula.75) During embryogenesis, periderm cells of the fetus contain which of the following substances?A. CeramideB. SebumC. GlycogenCorrect ChoiceD. Free fatty acidsE. PorphyrinsIn week 7 of embryogenesis the surface ectoderm produces two layers. The external layer is theperiderm which contains glycogen and gives rise to the stratum corneum by week 21. The otherlayer is the stratum germinativum.76) The desmosomal connections of the epidermis are dependent on which of the following ions?A. CalciumCorrect ChoiceB. IronC. ZincD. SodiumE. Selenium 21
  • The desmosomal connections in the epidermis are calcium dependent. The other options are notrequired for these connections.77) Surgery, Parturition, Fever, Kwashiokor and Hypervitaminosis A are all causes of:A. Telogen effluviumCorrect ChoiceB. Alopecia areataC. Both telogen and anagen effluviumD. Anagen effluviumE. Androgenetic alopeciaAll of the listed stressors can induce telogen effluvium. Other causes include traction and somedrug exposures. Usually will only involve up to 50% of scalp hairs and will resolve within 2-3months78) Anchoring fibrils are primarily composed ofA. Type II collagenB. Type IV collagenC. Type III collagenD. Type VII collagen Correct ChoiceE. Type I collagenAnchoring fibrils are found in the sublamina densa and are made up of collagen type VII. Thiscollagen type is mutated in dystrophic epidermolysis bullosa, and targeted in epidermolysisbullosa acquisita and bullous lupus erythematosus79) Which eponym describes vestigial lines of pigmentary demarcation?A. dermatomeB. Langers linesC. lines of BlaschkoD. Fuchter linesCorrect ChoiceE. Wallaces linesFuchter lines are vestigial lines in which the dorsal surface has more melanocytes than ventralsurface. Wallaces lines are the well-demarcated lines around the margin of the foot and hand.80) Elaunin fibersA. run parallel in bands within the superficial papillary dermis.B. run parallel in bands within the reticular dermis. Correct ChoiceC. run perpendicular from the dermo-epidermal junction within the superficial papillary dermis.D. run perpendicular in bands within the deep dermis.E. run perpendicular in bands within the reticular dermis. 22
  • Elaunin fibers are elastic fibers that have less elastin and more fibrillin and run parallel in thinbands within the reticular dermis. Oxytalin fibers contain no elastin and run perpendicular fromthe dermo-epidermal junction within the superficial papillary dermis. Elastic fibers turn over slowlyin the skin, and are damaged by ultraviolet radiation.81) Sebaceous glands secrete sebum through which of the following secretory mechanisms?A. Holocrine and MerocrineB. MerocrineC. Holocrine and ApocrineD. HolocrineCorrect ChoiceE. ApocrineSebaceous glands exhibit holocrine secretion, whereby the sebocytes disintegrate in transit to thegland center, releasing their sebum contents. Merocrine secretion refers to the formation ofintracellular secretory vesicles that translocate to the apical cell surface for secretion. Apocrinesecretion refers to the process whereby secretory contents are packaged using the apical cellmembrane, and pinched off to achieve secretion.82) The cutaneous immunofluorescence pattern in patients with Senear-Usher syndrome is:A. intercellular IgG on guinea pig esophagusB. intercellular IgG and C3 and linear IgG and C3 along the basement membrane zoneCorrectChoiceC. linear IgG and C3 along the basement membrane zoneD. linear IgG and C3 along the basement membrane zone and intercellular IgG on guinea pigesophagusE. intercellular IgG and C3Senear-Usher syndrome, or pemphigus erythematosus, is a variant of pemphigus foliaceuscharacterized by crusted papules and plaques with a seborrheic distribution (malar region, scalp,upper chest and back). They demonstrate in-vivo IgG and C3 deposition on keratinocyte cellmembranes and the basement membrane zone, in addition to circulating anti-nuclear antibodies.83) Sebaceous glands secrete sebum viaA. ExostosisB. Endocrine mechanismC. Exocrine mechanismD. Holocrine mechanismCorrect ChoiceE. Mecrocrine mechanismThe sebaceous lobules have basal germinative cells and central sebocytes, which graduallybecome more distended with lipid vacuoles until they are shed into the lumen (holocrinesecretion).84) Which of the following is not a specialized type of sebaceous gland? 23
  • A. Fordyce spotB. Montgomerys tubercleC. Meibomian glandD. Gland of ZeisE. Molls glandCorrect ChoiceThere are several types of specialized sebaceous glands that are not associated with a hairfollicle. They include Montgomerys areolar tubercle, Fordyce spots of the lip, Glands of Zeis ofthe cutaneous eyelid, and Meibomian glands of the eyelid. Molls gland of the eyelid are amodified apocrine gland.85) Keratohyalin granules containA. Envoplakin and Keratin 6B. Numerous Golgi apparatiC. DesmoplakinD. Profilaggrin and loricrin Correct ChoiceE. InvolucrinKeratohyalin granules are found in the stratum granulosum (the granular layer), and contain theproteins profilaggrin and loricrin. Profilaggrin is converted to filaggrin during the transformation ofthe granular layer to the cornified layer. This is a calcium-dependent process. Loricrin comprises75% of the cornified envelope’s mass.86) Which cadherin is responsible for adhesion of Langerhan cells to the epidermis?A. DesmocollinB. E-cadherinCorrect ChoiceC. P-cadherinD. N-cadherinE. DesmogleinE-cadherin is responsible for the adhesion of Langerhan cells to the epidermis. There are twomajor subclasses of cadherins which mediate cell adhesion and play a fundamental role innormal development, classic (E-,P-,N-cadherin) and desmosomal (desmoglein and desmocollin).They depend on calcium for their function.87) Anagen effluvium is best described asA. a cessation of mitotic activity in rapidly dividing hair matrix cells Correct ChoiceB. a scarring alopecia affecting only anagen stage folliclesC. a cessation of mitotic activity in resting hair matrix cellsD. an abrupt transition of telogen to anagen in resting hair matrix cellsE. an abrubt transition from anagen to catagen in rapidly dividing hair matrix cellsAnagen effluvium results from an outside stimulus – most often an antimetabolite,chemotherapeutic drug – inducing an abrupt cessation of hair matrix cell mitotic activity. This 24
  • process occurs within days to weeks of the stimulus, and is reversible with cessation of the drugtherapy.88) Retinoids upregulate transcription of which types of collagen?A. 1 and 7Correct ChoiceB. 3 and 7C. 4 and 7D. 1 and 3E. 1 and 4Retinoids upregulate the transcription of collagens one and seven thereby strengthening thedermis89) In the epidermis, the cell most responsible for antigen detection and processing is theA. MelanocyteB. Merkel CellC. Langerhans cell Correct ChoiceD. CD4+ T cellE. KeratinocytesThe Langerhans cell is a bone-derived, antigen-presenting cell found in all layers of theepidermis, oral mucosa, esophagus, and vagina. Langerhans cells ingest and process antigens,mature, migrate to a local lymph node, and then present the antigen to a naïve (or resting) T cell,activating that T cell. The Langerhans cell is central to the pathogenesis of atopic dermatitis,psoriasis, allergic contact dermatitis, and certain infections, such as Leishmaniasis.90) The formation of granulation tissue depends on the presence ofA. platelets.B. collagen type I.C. collagen type IV.D. fibronectin. Correct ChoiceE. neutrophils.See discussion of wound healing from questions 29 through 33.91) People with darker skin showA. a grouping of melanosomes with a low degree of melanizationB. a lessened production of melanosomes within melanocytesC. a higher degree of dispersion of melanosomes in keratinocytes Correct ChoiceD. smaller, more concentrated melanosomesE. a more rapid degradation of melanosomes 25
  • More darkly pigmented races show a greater production of melanosomes in the melanocyte,melanosomes with a higher degree of melanization, larger melanosomes, a higher degree ofdispersion of melanosomes in the keratinocytes, and a slower rate of melanosome degradation.92) Which of the following enzymes does not require copper for functioning?A. tyrosinaseB. cystathione beta-synthaseC. ferrochelataseCorrect ChoiceD. lysyl oxidaseE. ATP7aAll of the listed enzymes are copper containing or dependent except ferrochelatase. Lysyloxidase facilitates crosslinking of fibrillin in elastic fibers. ATP7a is deficient in Menkes Kinky HairSyndrome. Cystathione beta-synthase is defective in homocystinuria. Tyrosinase catalyzes thefirst 2 steps, and at least 1 subsequent step, in the conversion of tyrosine to melanin.Ferrochelatase mutation leads to excess protoporphyrin production and photosensitivity.93) When do melanocytes begin to synthesize melanin?A. 2nd month of gestationB. 4th month of gestationC. 3rd month of gestationCorrect ChoiceD. 6th month of gestationE. 5th month of gestationMelanocytes begin to synthesize melanin in the 3rd month of gestation.94) Red or blonde hair pigmentation primarily results fromA. the reduced activity of DOPA dehydroxylase.B. the presence of eumelanin.C. the presence of pheomelanin. Correct ChoiceD. the reduced activity of tyrosinase.E. the absence of melanin.Hair color is determined by melanocytes. The melanocytic activity of follicular melanocytes iscoupled to anagen – hair is only pigmented when it is growing. Pigment is produced in the matrixarea of follicle, above the follicular papilla. Eumelanin is the pigment of brown/black hairs, andpheomelanin is the pigment of red/blonde hairs. Intensity of color is proportional to the amount ofpigment. The absence of pigment produces white hair, and markedly reduced pigment producesgray hair.95) Sebaceous glandsA. respond to adrenergic neural activity, exclusively.B. respond to the local release of cytokines from inflammatory cells. 26
  • C. respond to chemical stimuli such as hormones. Correct ChoiceD. respond to cholinergic neural activity, exclusively.E. respond to both adrenergic and cholinergic stimuli.Sebaceous glands are androgen-responsive holocrine glands that enlarge at puberty. Meibomianglands of the eyelids are modified sebaceous glands. Sebaceous glands are found everywhereon the skin except the palms and soles. Fordyce’s condition involves free sebaceous glands onthe vermillion border of the lips and on the buccal mucosa. Eccrine glands are thermoregulatorystructures that respond to cholinergic stimulation.96) Anchoring filaments originate at the hemidesmosomes and insert into theA. Sub basal dense plateB. BPAG 180C. Lamina lucidaD. Lamina densaCorrect ChoiceE. DesmosomeAnchoring filaments (smaller than anchoring fibrils) stretch from the plasma membrane throughthe subbasal dense plaque and the lamina lucida to the lamina densa97) Keratinocytes are derived from which of the following:A. EndodermB. Neural CrestC. Bone marrow precursorsD. EctodermCorrect ChoiceE. MesodermAs implied by the root ecto, a prefix meaning "outer", the keratinocytes of the epidermis arederived from the ectoderm. The other layers do contribute cell populations that are present in theskin. 27