[ ] Pathology_of_Skin_Dis

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[ ] Pathology_of_Skin_Dis

  1. 1. Pathology of Skin Diseases Components of the Skin: 1. epidermis- consists of a number of layers listed from surface to base stratum corneum, stratum granulosum, stratum spinosum, and basal layer - top most layer is composed of keratin –squamous cells are connected by desmosomes 2. cell types- keratinocytes, basal cells, melanocytes (produce melanin in basal layer), langerhans cells (dendrite cells in epidermis that have an immunologic fxn) 3. Basement membrane zone (BMZ)- interface between the dermis and the epidermis 4. Dermis- contains BV’s, nerves, and skin appendages 5. Skin appendages- sweat glands, hair follicles, and sebaceous glands- located in the dermis 6. Subcutaneous fat (adipose tissue)- lies b/t the dermis and the underlying fascia -rete ridge is located in the basal cell layer ---melanocytes are located in the rete ridge Summary: Viral- verrucae, molluscum contagiosum, Herpes Bacterial- staph, strep Fungal- tinea, candidiasis Mites- scabies, pediculosis Infection and Infestation Verrucae (warts) • Common lesions • Caused by papilloma virus • Common in kids and adolescents • Transmission is via direct contact • Classification: 1. verruca vulgaris- common wart, occur anywhere on skin, but most common on dorsum of hand and fingers 2. verruca plana- flat wart, slightly elevated papules, often on face 3. verruca plantaris and verruca palmaris- scaly lesions on soles and palms 4. condyloma acuminatum- cauliflower like papillomas ---aka venereal warts---found on gential and perianal regions—can be on lips esp seen in the immunocompromised (AIDS) • histologically---seen as papillomatous epidermal hyperplasia with koilocytosis (cytoplasmic vacuolization-seen halo around nucleus) of superficial keratinocytes • acanthosis, hyperkeratosis, and parakeratosis (presence of nuclei in the keratin layer) are also present • viral cytopathic effects produce intracytoplasmic keratin aggregates • EM  numerous viral particles within the nuclei • There are diffenent types of papillomavirus- some viruses are oncogenic---asso with in situ squamous cell carcinoma Molluscum Contagiosum • Caused by the pox virus • Papular skin lesion- raised nodule (while macules are flat lesions) • Transmitted by direct contact • Pink umbilicated papules that have a cup like umbilication (center is depressed) • Cup like epidermal hyperplasia of cells with cytoplasmic inclusions molluscum bodies------ numerous virions are present within the molluscum bodies Note- verrucae intranuclear
  2. 2. Molluscum intracytoplasmic Staphylococcal Infections (S. Aurueus and or S. Epidermidis) 1. Scalded Skin Syndrome 2. Impetigo- superficial skin infections usually due to staph aureus causing subcorneal pustule which break down to form crusts ----pustules contain gram + cocci and neutrophils 3. Furuncle- (Boil)- pus filled nodule in the dermis, usually S. Aureus-----begins as folliculitis and enlarges into an abscess which ruptures through the epidermis 4. Carbuncle- necrotizing infection of the skin and sub Q, composed of a cluster of furuncles, with deeper suppuration and multiple drainage sinuses ---usually on back and neck Dermatologic Features of HIV (AIDS) • Mainly Kaposi’s sarcoma and opportunistic infections 1. Infections- (bacterial, fungi, and viral)- herpes and candidasis 2. Tumors- Kaposi’s sarcoma ---most common derm feature of AIDS 3. others- pupura, pigmentation, oral aphthae Acute Inflammatory Dermatoses 1. Urticaria (Hives) • Common irritating rash characterized by wheal formation resulting from mast cell degranulation  increased capillary perm with release of plasma into skin and subQ • Mainly occurs in young adults (age 20-40) • Mediated by IgE • Mast cell degranulation is caused by the direct action of chemicals, drugs, or insect bites • Sites- trunk, distal extremities, and ears 2. Acute Eczematous Dermatitis – 5 main types-clinicians will discuss these • Early lesions spongiosis, lymphocytic infiltration of the dermis, eosinophils present in infiltrate in drug-related dermatitis 3. Erythema Multiforme • uncommon • produced by allergic reaction to drugs, infections (mycoplamsa, histoplasmosis), malignancy (carcinomas), collagen vascular diseases (SLE, dermatomyositis) • clinical- lesions are widespread and may present as macules, papules, vesicles, and bullae (adjacent vesicles joined together) • target lesion –red macule or papule with pale vesicular or eroded center • symmetric involvement of extremities common (bilateral) • Steven Johnson Syndrome- severe form of erythema multiforme, more common in children, characterized by bleeding and serosanguinous crusting of lips and oral mucosa ---conjunctiva may be affected----asso with mycoplamsa infection • Mac Apperance- keratinocyte degeneration and necrosis vesiculation -target lesion surrounded by perivenular inflammation -mononuclear cell infiltration esp around BV’s 4. Erythema Nodosum • Most common cause of panniculitis- inflammation of subQ tissue predominately affect connective tissue septa or fat lobules • Acute onset asso with infections (strep, TB, histoplasmsmosis), drugs (sulfonamides, OC’s, sarcoidosis, IBD • Lesions are poorly defined, very tender, erythematous nodules involving the lower legs • No residual scars • Micro appearance- septa widening with edema, fibrin deposition and neutrophilic infiltration • No vasculitis
  3. 3. 5. Erythema Induratum • Uncommon panniculitis • cause unknown • primarily effects adolescents and menopausal women • lesion- erythematous, ulcerates and scars • Mic. Appearance- necrotizing vasculitis followed by granulomatous inflammation and necrosis –necrosis of adipose Chronic Inflammatory Dermatoses • Persistant chronic inflammatory dermatoses over months or years characterized by excessive or abnormal scale formation and shedding 1. Psoriasis • Sites-elbows, knees, scalp-----usually bilateral • Pink plaques covered with silvery scales • May have nail changes like pitting, thickening, and separation of the nail bed (onycholysis) • Rarely get pustules formed on plaques  pustular psoriasis • Joints may be involved • Mic. App- 1. acanthosis-hyperplasia of squamous layer of epidermis---with elongated rete ridges 2. paraketosis- nuclei present in the keratin layer 3. munro abscesses- collections of neutrophils within the superficial epithelium 4. dilated BV’s in dermisclinical erythema Auspitz sign- punctate bleeding • cause-unknown---probably mulitfactorial • etiological hypothesis: 1. genetic- certain HLA types 2. trauma- Koebner phenomenon- when lesions appear at site of trauma 3. immune basis-presence of activated T-lymphocytes 2. Lichen Planus • Common • Violaceous papules with white dots or lines (Wickham’s striae) • Sites: wrists and elbows • Oral lesions common---bucal mucosa and lateral part of dorsum of tongue • Mic app: 1. parakeratosis 2. saw tooth pattern of deep surface of epithelium 3. liquefaction degeneration at DE junction 4. anucleate, necrotic basal cells  colloid or civatte bodies 5. dermis- dense band like infiltrate of mononuclear cells (mainly T cells) in upper dermis • cause-unknown –maybe cell mediated immune injury to basal cells • age- 30-60, higher in females 3. Lupus erythematosus • Discoid lupus erythematosus (DLE)  Autoimmune  Localized cutaneous form of LE
  4. 4.  One third of patients with SLE lesions similar to DLE  Sites- face, neck, arms, and scalp  Erythematous scaling plaques  Keratotic plugs  Mic app- edema of DE junction, thickening of BMZ  Direct IF shows granular band of immunoglobulin (IgM) and complement along DE jxn: lupus band test 4. Acne Vulgaris • Most common skin disease seen in derm practice • Did not cover in class- will be covered by clinicians Blistering (Bullous) Diseases • Group of diseases in which blisters are primary and most distinctive feature • Blisters (vesicles or bullae) occur as secondary phenomenon in herpes virus infection, erythema multiforme, thermal burns, etc 1. Pemphigus vulgaris- most common type, affects both mucosa and skin • Vesicles and bulla form • Mac app- all 4 variants (she only talked about this one type in class) show acantholysis- lysis of intercellular bridges --> clefts and intraepithelial blisters . In P. vulgaris- suprabasalar acantholytic blisters • IF shows intercellular deposits of IgG and complement 2. Bullous Pemphigoid • Subepithelial bullae of skin and mucosal surfaces • Mic app- nonacantholytic blisters • IF testing shows linear BMZ deposits of IgG and complement 3. Dermatitis Herpitiformis • Sites: extensor surfaces, oral mucosa not affected • Subepidermal bullae • Microabcesses in dermal papillae • IF testing shows granular deposits of IgA at tips of dermal papillae • May be asso with celiac disease • Ind with HLA-B8 and HLA-DRW3-particularly prone to this disease Dr. Khin said this wouldn’t be on exam but then she asked it in her review questions so I have included it. Erysipelas • Group A strep or Staph Aureus • Cellulites- dermis and subQ Erysipeloid (fish handlers disease, crab dermatitis) • Gram pos rod Review Questions 1. Verrucae warts are caused by _______________ also known as ________________ 2. Koilocytosis means _________________ and is asso with _____________________ 3. _____________________are seen in Molluscum contagiousum 4. Scalded Scale Syndrome is caused by ____________________ 5. Carbucle is best described as ______________________ 6. Difference b/t erysipelas and erysipeloid is ___________________________
  5. 5. 7. True or False – Intranuclear inclusions are seen in papilloma virus infection 8. Target lesions are characteristically seen in ________________________ 9. Erythema Nodosum and induratum are inflammation of ____________________ 10. Mycoplasma infection may lead to ______________________________ Answers: 1. papilloma virus, 2. cytoplasmic vacuolization, halo around nucleus-------asso with verrucae 3. umbilicated papules caused by pox virus 4. staph 5. necrotizing infection of the skin and sub Q, composed of a cluster of furuncles, with deeper suppuration and multiple drainage sinuses ---usually on back and neck 6. see explanation above 7. true 8. erythema multiforme 9. panniculitis 10. steven Johnson syndrome More review questions: see noteservice for actual questions- I only wrote down key words 1. target lesions- seen with erythema multiforme 2. erythema nodosum and induratum- common feature is panniculits 3. Monroe abscess- psoriasis 4. Auspitz sign 5. micro features of lichen planus-parakeratosis, saw tooth appearance of deep surface of epithelium, liquifaction degeneration at DE jxn, anucleate, necrotic basal cells, and dermis has band like infiltrate of mononuclear cells in upper dermis 6. IF studies of affected lesion is pemphigus vulgaris shows –deposits of IgA and complement 7. granular deposits of IgA seen at tips of dermal papillae are seen in 8. bullous pemphigoid shows linear BMZ deposits 9. furuncle-(Boil)- pus filled nodule in the dermis, usually S. Aureus-----begins as folliculitis and enlarges into an abscess which ruptures through the epidermis 10. wickman’s straie seen in lichen planus 11. lupus band test used in DLE 12. acantholysis is seen in pemphigus
  6. 6. 7. True or False – Intranuclear inclusions are seen in papilloma virus infection 8. Target lesions are characteristically seen in ________________________ 9. Erythema Nodosum and induratum are inflammation of ____________________ 10. Mycoplasma infection may lead to ______________________________ Answers: 1. papilloma virus, 2. cytoplasmic vacuolization, halo around nucleus-------asso with verrucae 3. umbilicated papules caused by pox virus 4. staph 5. necrotizing infection of the skin and sub Q, composed of a cluster of furuncles, with deeper suppuration and multiple drainage sinuses ---usually on back and neck 6. see explanation above 7. true 8. erythema multiforme 9. panniculitis 10. steven Johnson syndrome More review questions: see noteservice for actual questions- I only wrote down key words 1. target lesions- seen with erythema multiforme 2. erythema nodosum and induratum- common feature is panniculits 3. Monroe abscess- psoriasis 4. Auspitz sign 5. micro features of lichen planus-parakeratosis, saw tooth appearance of deep surface of epithelium, liquifaction degeneration at DE jxn, anucleate, necrotic basal cells, and dermis has band like infiltrate of mononuclear cells in upper dermis 6. IF studies of affected lesion is pemphigus vulgaris shows –deposits of IgA and complement 7. granular deposits of IgA seen at tips of dermal papillae are seen in 8. bullous pemphigoid shows linear BMZ deposits 9. furuncle-(Boil)- pus filled nodule in the dermis, usually S. Aureus-----begins as folliculitis and enlarges into an abscess which ruptures through the epidermis 10. wickman’s straie seen in lichen planus 11. lupus band test used in DLE 12. acantholysis is seen in pemphigus

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