Dermatology Topics Lecture Notes*


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Dermatology Topics Lecture Notes*

  1. 1. Dermatology Topics Quinnipiac University Physician Assistant Program Fifths Disease Definition: •benign, self-limited rash caused by Parvovirus B19 (also called Erythema Infectiosum) Epidemiology: •age of onset: peaks between 5 - 15 years of age •risk factors: M = F Pathogenesis History •1975 - human parvovirus B19 first discovered •1981 - B19 parvovirus not associated with a disease until 1981 •1983 - B19 parvovirus associated Fifth Disease •1984 - found to be a source of intrauterine infection •1985 - associated with some forms of acute arthritis •parvovirus B19 tends to lead to a transient anemia •parvovirus B19 may also cause an asymptomatic infection, a mild respiratory illness, an atypical rash, arthritis •incubation period between 4-21 days (period of time from the acquisition of infection to onset of the initial symptoms) •persons are most infectious during the incubation period and are unlikely to be infectious after the onset of the rash Route of Transmission •humans are the only known host for parvovirus B19 and the virus is transmitted by human-to-human contact via respiratory secretions or by blood (and blood products) •infections occur sporadically or as community outbreaks (usually in elementary or junior high schools in the spring) •parvovirus B19 infection is most common in school age children and greater than 50% of adults have serologic evidence of past infection •persons at risk: teachers, day-care workers, pediatric health-care providers •there is a 9-10% risk of fetal hydrops or death if infection is acquired by a seronegative mother within the first 20 weeks of pregnancy •the incidence of fetal hydrops or death is less than 10% if an in utero infection is acquired in the second half of pregnancy
  2. 2. Clinical Features Prodrome •proceeds the rash by 7-10 days •mild respiratory tract symptoms •headache •low grade fever •malaise •myalgia •pharyngitis Skin Manifestations 1) First Stage •classic "slapped cheek" - the cheeks are intensely red and associated with circumoral pallor 2) Second Stage •a diffuse macular red rash appears on the trunk and proximal extremities (i.e., upper arms and legs) •rash is more prominent on the extensor surfaces of the extremities •soles and palms are spared 3) Third Stage •central clearing of the macular lesions gives the rash a lacy, reticulated appearance •the rash waxes and wanes over 1-3 weeks then resolves spontaneously •not associated with desquamation •rash can recur with exercise, stress, heat, and/or exposure to sunlight Investigations 1) Serology •B19 IgM Antibody Test –monoclonal antibodies with radioimmunoassays and ELISA –the presence of B19 IgM antibody confirms infection within the past several weeks •the presence of serum IgG antibodies indicates previous infection and immunity Henoch-Schoenoch Purpura (HSP) Definition: •vasculitic syndrome of small vessels classically characterized by a purpuric rash, abdominal pain, arthritis, and nephritis Epidemiology: –most common form of systemic vasculitis in children –age of onset: 75% of cases between 2 - 11 years of age; mean of 5.5 years, milder disease in those <2 years
  3. 3. –risk factors: M > F (2:1) –spring and autumn –whites > blacks Clinical Features Classical Features •100% - rash (nonthrombocytopenic purpura) •68% - arthritis •53% - abdominal pain •38% - nephritis Classic Rash (100%) •presenting feature in 50% of cases •urticarial wheals, erythematous maculopapules and/or larger palpable ecchymotic- looking lesions •appear on lower extremities and buttocks •may involve upper extremities, face, and trunk Petechiae or Purpura Lesions •evolve from red to purple -> rust-coloured with brownish hue -> fade Arthritis/Arthralgia (68-75%) •presenting feature in 25% of cases •tends to be periarticular •no bleeding or effusion into joints •joints swollen, tender, and painful •ankles and knees most commonly affected •rarely fingers and wrists involved •transient but may recur during active disease •no permanent deformation Gastrointestinal Manifestations •abdominal pain (35-85%) •3rd most common presenting complaint •severe colicky pain with vomiting •usually follows onset of rash and joint pain Renal Manifestations •occur in 20-50% of cases •develop within 3 months of the onset of rash but in 3% of cases may precede rash •renal involvement more likely with: –gastrointestinal involvement •complications:
  4. 4. –persistent nephropathy in 1% Treatment NSAID's –for joint and soft tissue pain Corticosteroids •Prednisone not recommended for: –rash –joint pain •Nephropathy –fluid & electrolyte balance, moniter salt intake –antihypertensives Prognosis •Excellent –if no renal or neurologic manifestations or microscopic hematuria –lasts 4-6 weeks in a majority of cases –recurrences in 50% within 6 weeks but as late as 7 years –children <3 years have a shorter, milder course with fewer recurrences Henoch-Schoenoch Purpura (HSP) COLITIS Definition: •systemic disease (vasculitis) involving the colon and which may result in an intestinal inflammatory disorder Epidemiology: •same as of Henoch-Schoenlein Purpura Pathogenesis Etiology •an unknown antigenic stimulant (infectious agent, drugs, cold) causes an elevation of IgA •activates pathways leading to an IgA-mediated necrotizing vasculitis in the small vessels of involved organs •in the GI tract, this leads to a mesenteric vasculitis •subsequent submucosal and intramural extravasation of fluid and blood into the intestinal wall results in abdominal pain •eventually to localized mucosal ulcerations and bloody stool •the intussusception associated with HSP is secondary to submucosal hematomas Gastrointestinal Manifestations •occur in 35-85% of patients with HSP
  5. 5. •usually follow rash & joint pain (may precede rash in 14% of cases) •abdominal pain - severe colicky pain with vomiting •bloody diarrhea - gross or occult with hematemesis •intussusception Kawasaki‘s Syndrome Definition: •vasculitic syndrome of large-medium vessels classically characterized as an acute febrile illness associated with a systemic vasculitis Epidemiology: •incidence: 1-10/100,000 •age of onset: peak age is 1-3 years •80-85% <5 years; seldom >7 years; rare >11 years •Tomasaku Kawasaki described the disease which is named after him in 1967 yet the cause of Kawasaki Disease remains unknown • KD, originally called mucocutaneous lymph node syndrome, is a systemic febrile vasculitis predominantly affecting children under 4 years •KD is much more •etiology of KD remains unknown •acute, febrile, and self-limited nature and •clinical manifestations of: –rash –meningeal –hepatic –joint –mucous membrane inflammation •strongly suggest an infectious etiology or trigger •predominance of cases in children under 12 years of age and the occurrence of community-wide epidemics further suggest that the etiologic agent may be common and widely distributed •despite lack of the identification of an etiologic agent, intravenous gamma globulin (IVIG) has been discovered as a remarkably effective treatment resulting in rapid clinical improvement and prevention of coronary artery sequelae Clinical Features Principal Symptoms •1. fever (persisting 5 days or more) •2. bilateral conjunctival exanthema •3. oral mucosal changes
  6. 6. •4. cervical lymphadenopathy •5. peripheral extremity changes 1) Fever •earliest symptom •remittent (39.5-40.5 C), high spiking, prolonged •does not respond to antibiotic therapy •resolves within 2-3 days of starting high dose ASA 2) Bilateral Conjunctival Exanthem •begins shortly after onset of fever, lasts 1-2 weeks •bulbar conjunctivitis with vascular dilation but no exudate or palpebral involvement 3) Oral Mucosal Changes •red, swollen, dry, fissured lips •"strawberry tongue" •diffuse erythema of oral & pharyngeal mucosa 4) Cervical Lymphadenopathy •posterior cervical lymphadenopathy (50-75%) •acute and nonpurulent; at least one node >1.5 cm •tender, rarely red, fluctuant, torticollis 5) Peripheral Extremity Changes (acute stage) •reddening of palms and soles •indurative edema & tenderness of hands and feet 6) Polymorphous Rash •begins within 5 days after onset of fever •fine, erythematous, morbilliform generalized rash •intense, desquamating rash in perineum (25-50%) Cardiovascular Manifestations (20%) •within first 10 days of onset of fever •myocarditis/endocarditis •arrhythmias, gallop rhythm, CHF with shock •pericarditis •pericardial effusion •cardiac tamponade (Beck's Triad - hypotension, distended neck veins, diminished heart sounds) Pathologically •KD is a multisystem vasculitis with a predilection for the coronary arteries
  7. 7. •acute phase (first 10 days of illness) is characterized by an intense inflammatory infiltrate of the coronary arteries •some patients may develop congestive heart failure and myocardial dysfunction, but death during this phase is usually sudden and thought to be due to arrhythmia •during the convalescent phase (10-40 days after the onset of fever) the inflammatory infiltrate matures from predominantly polymorphonuclear leukocytes to a predominance of mononuclear cells •coronary artery involvement is usually bilateral and most severe near the origin (proximal) •death is most frequently due to acute myocardial infarction due to acute coronary artery thrombosis Coronary Artery Vasculitis •dilatation +/- aneurysms (20-40%) •first detected at a mean of 10 days •peak occurrence at 3-4 weeks after onset •50% of aneurysms resolve by 18 months •thrombosis and stenotic lesions -> angina, MI •ruptured coronary aneurysm -> hemopericardium •major complication of KD is coronary artery involvement, predominantly aneurysm formation, which occurs in 20 - 30% of patients •with the decline in rheumatic heart disease, KD is now the commonest cause of acquired heart disease in developed countries •myocardial infarction, aneurysm rupture and dysrhythmias account for the deaths in the acute phase of the illness CSF •aseptic meningitis •mononuclear pleocytosis (25-100 WBC) •normal or slightly elevated protein •normal glucose Treatment Supportive •hydration therapy if dehydrated •pain control Medications •gammaglobulin (IVGG) •high dose ASA
  8. 8. •100 mg/kg/day po qid until afebrile for 24-36 hours •institution of IVGG and ASA within 10 days of fever onset reduces the incidence of coronary artery lesions from 18% to 4% •prompt clinical improvement follows IVIG: 60% become afebrile within 12 hours of IVIG, and 90% within 48 hours •risk of coronary aneurysms has been lowered from 18-25% to 2-4%. Infants younger than 1 year of age have the highest risk of coronary abnormalities when untreated •even with IVIG treatment, the risk of coronary abnormalities at 8 weeks is 15% •therapy consists of intravenous infusion of IVIG 2 gm/kg given over 10-12 hours •aspirin therapy should be instituted on the day IVIG is given –dose of 100 mg/kg to a maximum of 4 grams per day is given until a few days after defervescence or until the 14th day of illness •followed by a daily dose of 3 to 10 mg/kg/day (one half to one 81 mg tablet) until the ESR and platelet counts return to normal –anti-coagulation with low dose aspirin therapy helps prevent the thrombosis in the setting of vascular inflammation and elevated platelet counts •can be interrupted in children who develop varicella or influenza during the follow-up phase to decrease the risk of Reye syndrome Urticaria (Hives) Definition: •inflammatory disorder within the skin often initiated by an IgE-mediated hypersensitivity Epidemiology: •incidence: 10% of children •age of onset: any •risk factors: F > M Pathogenesis •allergy is the manifestation of a hypersensitivity reaction to the presentation of an allergen due to the propensity of the affected individual to develop a sustained IgE response following antigenic stimulation •there are several types of allergies based upon where the hypersensitive reaction occurs: •Surface - Allergy •Nasal Mucosa - Allergic Rhinitis •Respiratory Tract- Allergic Asthma •Systemic - Anaphylaxis •Skin - Hives (Urticaria), Atopic Dermatitis
  9. 9. Occurrence of Urticaria •Affects 20% to 25% of the population at some time in their lives1 •50% remission <1 year2 •40% of cases lasting >6 months are likely to last ≥10 years2 IgE-Mediated Urticaria •an allergy specific to the skin in susceptible individuals allergens •infections –bacterial, viral (hepatitis, infectious mononucleosis) fungal, parasitic •drugs –penicillin, sulfa drugs, phenytoin, barbiturates, ASA •foods –nuts, shellfish or seafood, chocolate, dairy products (milk, eggs) Atopic Dermatitis (Eczema) Definition: •inflammatory disorder of the skin initiated by an IgE-mediated hypersensitivity. Epidemiology: •incidence: 2-5% of children •age of onset: 80% of patients present by 1 year of age (rare before 2 months) •risk factors: 67% have a positive family history of atopy (asthma, hayfever, urticaria) •50-80% of patients with atopic dermatitis will go on to develop asthma and/or allergic rhinitis, i.e., atopic dermatitis may be the forerunner for the development of other allergic diseases Clinical Features •atopic dermatitis typically occurs in 3 stages each with fairly distinctive features •the eczema may be called the "itch that rashes" –first symptom is itchiness of the skin with the subsequent appearance of the rash which is made worse by further scratching ("itch-scratch-rash-itch-cycle") Stage 1 - Initial Phase •Onset –birth to 2 years of age with a mean of 8 months •Rash –intense pruritis with scratching –diffuse erythematous flush –erythematous weeping patches (diaper area spared) –dry, red, scaly plaques
  10. 10. •Distribution –cheek with spread to face, scalp, behind ears, neck –extensor surfaces of the extremities (arms, wrists, hands, legs) and the abdomen Stage 2 - Childhood Phase •Onset –2 to 12 years of age •Rash –intense pruritis with scratching –papules coalesce to form plaques –marked excoriation and lichenification (thickening) •Distribution –face (eyes, mouth), behind ears –flexural surfaces of the neck, antecubital and popliteal fossae, and wrists and ankles Stage 3 - Adult Phase •Onset –greater than 12 years of age •Rash –diffuse, scaling, dried, lichenified, hyperpigmented •Distribution –whitish hue on forehead, upper eyelids (mask of atopic dermatitis) –flexural surfaces of the neck, antecubital and popliteal fossae –dorsal aspects of hands and feet Management •recognize that eczema is a chronic condition with periods of remission •during times of relapse may need reassurance and morale boosting •eczema tends to improve with age •management is based on: –avoidance –reduce or eliminate itch –medications