Objectives Identifying Typical Skin Rashes Nora Lin, MD Terminology A. Papule/Plaque: Small, raised, palpable lesions <1cm/>1cm. Can be solitary or multiple B. Macule/Patch: <1.5 cm area of color change, with smooth surface C. Morbilliform: mixture of macules and papules, coalescing, resembles measles rash D. Vesicle/Bulla: Like A, but containing fluid. E. Nodule: palpable, solid, deeper than A F. Wheal: pale, red, palpable superficial lesion, evanescent • Recognize some common dermatologic conditions seen in the office setting • Recognize morphologic and distribution patterns of rashes • Learn key historical questions to ask when identifying rashes Papulovesicular • 23 yo M with itchy rash for 4-5 weeks, now getting worse. • Initially improved with hydrocortisone, then worse • Rash on genitals too • Nonatopic • Very itchy at night, zyrtec not helping • Girlfriend now getting similar rash • Diagnosis: Scabies G. Pustule: Like D, but with purulent exudate as the fluid 1 Scabies • Excoriated papules, vesicles, nodules • Distribution DDx • Bedbugs or flea bites – Bed needs to be inspected; small infestations may be hard to detect – Adults: Finger webs, wrists, extensor surfaces of elbows/knees, buttocks, genitalia, waist, ankles – Infants: more generalized – Pathognomonic burrows • Miliaria rubra (heat rash) • Treatment – Erythematous papules and pustules from obstructed sweat – Topical permethrin or oral ivermectin, antihistamines, Tx family/contacts Papulosquamous Pityriasis rosea • • 17 yo F presents in June w/ pink, “bumpy” rash on the torso • Just got over a mild cold • No one else at home affected • Mildly itchy • Hx of mild spring allergies • Diagnosis: pityriasis rosea • • • +/- viral prodome in ~50% cases Oval salmon colored “herald patch” usu. on the trunk 1-2 weeks later many smaller oval plaques appear along skin lines Tx: reassurance, self limited course (can be many weeks), supportive care Collarette scale 2 Annular DDx • Tinea • Nummular eczema – Can be solitary or multiple lesions – Scaly ring progresses outward Tinea corporis – Middle-aged, elderly – Back of hands, legs, hips common sites – Steroid responsive Erythema migrans Serum sickness Papulosquamous • 28 yo F says “I’ve always had itchy arms, but it’s been awful this winter” • Hx of asthma, seasonal allergies • Dx: atopic dermatitis Atopic Dermatitis • • Pruritus Typical distribution – Infants: facial/extensor – Older: flexural surfaces • Treatment – Avoid triggers • Allergens • Excessive bathing – Emollients – Topical anti-inflammatories • Steroids • Immune modulators (tacrolimus, pimecrolimus) 3 Eczema • • • • • Atopic dermatitis Contact dermatitis – irritant and allergic Nummular dermatitis Seborrheic dermatitis Lichen simplex chronicus Keratosis Pilaris (“chicken skin”) • • • Often associated with atopic dermatitis Posterolateral arms, thighs, face Treatment – Topical steroids – 12% ammonium lactate lotion (LacHydrin, AmLactin) – No abrasive techniques Eczema Allergic Contact Dermatitis Irritant Dermatitis Maculopapular • 10 mon old on day 5 of amoxicillin • Diffuse red rash • First time on amoxicillin • Exam wnl except for rash • Dx: amoxicillin allergy? Or viral exanthem? 4 Drug induced Rashes Viral Rashes (exanthems) Fixed drug eruption maculopapular erythema multiforme urticarial morbilliform Morbilliform • 18 yo presents with diffuse red rash, fever 101 • Few days earlier with cough, runny nose, “pinkeye” maculopapular erythema multiforme urticarial morbilliform Measles • Highly contagious • Incubation 7-14 days • Infection communicable 4 days before his rash appeared to 4 days after • Treatment conjunctivitis – Infection control – Immune globulin – Supportive care 5 Urticarial • 18 mon old with second occurrence of this rash • No associated viral symptoms at time of rash, but then fever, diarrhea came 5d later DDx of urticarial rashes Serum sickness Erythema multiforme Vesicopapular • Adolescent with generalized rash after low gr fever, chills, malaise 2d prior Varicella (chickenpox) • Lesions in different stages at the same time • Ask about vaccination status and immune deficient/pregnant household contacts 6 Conclusion • Generalists physicians encounter a wide variety of dermatologic lesions in a wide variety of stages. • History and clinical picture are often enough to make the diagnosis • Attempts at self-treatment present additional diagnostic challenges. • Most conditions are common and easily treated or selfresolve…but for those that are not… • Biopsies may be needed for definitive diagnosis. 7