A Photo Quiz to Hone Dermatologic Skills (June 2005)

Case 1: A 45-year-old woman presents for evaluation of increased pigmentation on the sides of her neck. The discoloration has been present for at least several months and is asymptomatic. What cause could explain the discoloration? A. Polymorphous light eruption. B. Poikiloderma of Civatte. C. Lentigines. D. Photodrug reaction. E. Contact dermatitis. Answer on next page , Case 1 Answer: Poikiloderma of Civatte, B, dermatoheliosis that results from a lifetime of exposure to sun, is characterized by telangiectasia and hyperpigmentation on the sides of the neck. It is seen most commonly in middleaged women. A polymorphous light eruption consists of discrete flat, erythematous papules on sun-exposed surfaces. Lentigines are discrete hyperpigmented macules that occur on sun-exposed areas. A photodrug eruption is usually erythematous and pruritic; it may affect the neck as well as other sunexposed surfaces. Contact dermatitis is pruritic and erythematous. Case 2 on next page , Case 2: For several months, a 63-year-old man has had an asymptomatic eruption on his trunk and proximal extremities. He denies any new medications or exposure history. He has taken the same antihypertensive medication for several years. What is your clinical impression? A. Pityriasis rosea. B. Nummular eczema. C. Parapsoriasis. D. Psoriasis. E. Contact dermatitis. Answer on next page , Case 2 Answer: The patient has parapsoriasis, C,  which is characterized by slightly scaling, erythematous oval patches on the trunk and proximal extremities. The lesions usually persist for years. Up to 10% of lesions larger than 5 cm may progress to T-cell lymphoma. A biopsy is typically necessary to confirm the diagnosis. Pityriasis rosea, nummular eczema, psoriasis, and contact dermatitis are usually symptomatic and feature more scaling. Case 3 on next page , Case 3: Six weeks earlier, this asymptomatic red papule arose on the trunk of a 67-year-old man with a history of basal cell carcinoma and actinic keratoses. He denies insect bite and trauma. What are you looking at here? A. Insect bite. B. Folliculitis. C. Actinic keratosis. D. Lichenoid keratosis. E. Basal cell carcinoma. Answer on next page , Case 3 Answer: A biopsy confirmed thediagnosis of lichenoid keratosis, D. These lesions usually appear as solitary erythematous, flat papules on sun-exposed surfaces of the upper extremities or upper chest. They are more common in women. On histologic examination, they sometimes show features of a resolving keratosis and an abundant lichenoid infiltrate. Insect bites and folliculitis are typically symptomatic. A biopsy is sometimes the only way to distinguish lichenoid keratoses from inflamed actinic keratoses or basal cell carcinoma. Case 4 on next page , Case 4: A 72-year-old man has had a highly pruritic rash in the groin for several weeks. He has type 2 diabetes mellitus, which has been controlled with an oral hypoglycemic agent for the past 5 years. He recently started a low-impact exercise program. Which of the following do you suspect? A. Intertrigo. B. Candidiasis. C. Tinea cruris. D. Contact dermatitis. E. Erythrasma. Answer on next page , Case 4 Answer: The patient has intertrigo, A,  which results from the friction of skin surfaces rubbing against each other. Intertrigo is a diagnosis of exclusion that is made when the results of a potassium hydroxide evaluation are negative and the patient does not respond to a course of antibiotics. Secondary infection can occur and must be ruled out. Drying agents that contain aluminum chloride or barrier creams, such as those that contain zinc oxide, are often effective. Contact dermatitis can be caused by detergents or fabric softeners and typically affects areas where clothing is tightest, such as the waist and axillae.