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D42 Dermatology
Miscellaneous Lesions
Toronto Notes 2019
DDx of Erythema Nodosum
NODOSUMM
NO cause (idiopathic) in 40%
Drugs (sulfonamides, OCP, etc.)
Other infections (GAS+)
Sarcoidosis
UC and Crohn’s
Malignancy (leukemia, Hodgkin’s lymphoma) Many Infections
Erythema Nodosum
Clinical Presentation
• acuteorchronicinflammationofsubcutaneousfat(panniculitis)
• round,red,tender,poorlydemarcatednodules
• sites:asymmetricallyarrangedonextensorlowerlegs(typicallyshins),knees,arms • associatedwitharthralgia,fever,malaise
Etiology
• 40%areidiopathic
• drugs:sulfonamides,OCPs(alsopregnancy),analgesics,transretinoicacid • infections: GAS, TB, histoplasmosis, Yersinia
• inflammation:sarcoidosis,Crohn’s>UC
• malignancy:acuteleukemia,Hodgkin’slymphoma
Epidemiology
• 15-30yrold,F:M3:1
• lesionslastfordaysandspontaneouslyresolvein6wk
Investigations
• CXR(toruleoutchestinfectionandsarcoidosis) • throatculture,ASOtitre,PPDskintest
Management
• symptomatic:bedrest,compressivebandages,wetdressings • NSAIDs,intralesionalsteroids
• treatunderlyingcause
Pruritus
Clinical Presentation
• asensationprovokingadesiretoscratch,withorwithoutskinlesions
• lesionsmayarisefromtheunderlyingdisease,orfromexcoriationcausingcrusts,lichenifiedplaques,or
wheals
Etiology
• dermatologic–generalized
■ asteatotic dermatitis (“winter itch” due to dry skin)
■ pruritus of senescent skin (may not have dry skin, any time of year) ■ infestations: scabies, lice
■ drug eruptions: ASA, antidepressants, opiates
■ psychogenic states
• dermatologic–local
■ atopic and contact dermatitis, lichen planus, urticaria, insect bites, dermatitis herpetiformis ■ infection: varicella, candidiasis
■ lichen simplex chronicus
■ prurigo nodularis
• systemicdisease–usuallygeneralized
■ hepatic: obstructive biliary disease, cholestatic liver disease of pregnancy
■ renal: chronic renal failure, uremia secondary to hemodialysis
■ hematologic: Hodgkin’s lymphoma, multiple myeloma, leukemia, polycythemia vera,
hemochromatosis, Fe deficiency anemia, cutaneous T-cell lymphoma
■ neoplastic: lung, breast, gastric (internal solid tumours), non-Hodgkin’s lymphoma ■ endocrine: carcinoid, DM, hypothyroid/thyrotoxicosis
■ infectious: HIV, trichinosis, echinococcosis, hepatitis C
■ psychiatric: depression, psychosis
■ neurologic: post-herpetic neuralgia, multiple sclerosis
Investigations
• bloodwork:CBC,ESR,Cr/BUN,LFT,TSH,fastingbloodsugar,stoolculture,andserologyforparasites
Management
• treatunderlyingcause
• coolwatercompressestorelievepruritus
• bathoilandemollientointment(especiallyifxerosisispresent)
• topicalcorticosteroidandantipruritics(e.g.menthol,camphor,phenol,mirtazapine,capsaicin) • systemicantihistamines:H1blockersaremosteffective,mostusefulforurticaria
• phototherapywithUVBorPUVA
• doxepin, amitriptyline
• immunosuppressiveagentsifsevere:steroidsandsteroid-sparing
DDx of Pruritus
SCRATCHED
Scabies
Cholestasis
Renal
Autoimmune
Tumours
Crazies (psychiatric)
Hematology (polycythemia, lymphoma) Endocrine (thyroid, parathyroid, Fe) Drugs, Dry skin
Consider biopsy of any nonhealing wound to rule out cancer