Dermatologist MCQs (Prometric)

A 66-year-old develops a symmetric lichenoid eruption several months after starting a new medication. Oral mucosa is spared, and the eruption is more widespread than typical idiopathic lichen planus. Which biopsy clue most favors a lichenoid drug eruption?

A healthy 5-year-old girl has had several painless thigh papules for two months. She has no fever, secondary infection, eczema, or immunodeficiency, and her parent prefers the least invasive approach if it is safe. The lesions are shown. What is the best management?

A 39-year-old woman has sharply localized chronic eczema beneath a metal watch clasp. Avoiding the watch clears the eruption, but it recurs within two days whenever she wears it again. Which mechanism best explains this reproducible reaction?

A 71-year-old with an implanted cardioverter-defibrillator requires electrosurgical control of a small bleeding vessel during skin surgery. Electrosurgery is necessary. Which setup best minimizes electrical current traversing the patient's body?

A child being evaluated for persistently elevated sweat chloride has the normal gland architecture shown. Which epithelial transport defect most directly produces the abnormal sweat composition?

A newborn develops blisters after routine handling and removal of adhesive monitoring tape. Epidermolysis bullosa is suspected, and subtype confirmation is pending. Which immediate skin-care measure is most appropriate?

A patient from an endemic region has a chronic well-demarcated hypopigmented plaque with reduced temperature and pinprick sensation and a palpably enlarged nearby peripheral nerve. Which test most appropriately confirms the suspected diagnosis?

A 48-year-old kidney-transplant recipient develops several slowly enlarging plaques on the lower legs. Biopsy is performed, and the H&E field is shown. Which diagnosis best accounts for the clinicopathologic findings?

A 73-year-old woman develops rapidly enlarging violaceous nodules confined to one lower leg. Biopsy demonstrates sheets of large CD20-positive B cells expressing BCL2 and MUM1, and systemic staging shows no extracutaneous lymphoma. The diagnosis is primary cutaneous diffuse large B-cell lymphoma, leg type. Which treatment is most appropriate?

A 55-year-old man reports increasing skin fragility on the dorsal hands after minor trauma. He drinks alcohol regularly and has noticed darker urine. The representative lesion is shown. Which laboratory approach should be used to confirm the suspected diagnosis?