A 60-year-old woman comes to the physician with 10 days of diffuse itching. A rash began on her hands and quickly spread to involve her wrists, arms, and axillae. She has difficulty sleeping and complains of intense itching in these areas. She works in a day care center and primarily takes care of children age 2-5. The patient has no other medical conditions and takes no chronic medications. Vital signs are normal. Her BMI is 24 kg/m². Skin examination shows small erythematous papules on the palms with excoriations, scattered vesicles, and pustules on the finger webs, palms, and wrist creases, as seen in the image below. She has similar lesions in her axillary skin folds bilaterally. The remainder of the examination is within normal limits. Which of the following is the most likely finding on skin sampling of this patient's lesions?

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11ec160b_37ec_31e5_9249_65c4307bcda1_MD0001_00 This patient's presentation - rapidly spreading, pruritic rash with erythematous papules and excoriations on the extremities - suggests scabies. Scabies is due to infestation by the Sarcoptes scabiei mite, which burrows into the skin and spreads through direct person-to-person contact. It usually presents with an intensely pruritic rash in the flexor surfaces of the wrist, lateral surfaces of the fingers, and the finger webs. The pruritus is often worse at night and is due to a delayed type IV hypersensitivity reaction to the mite, mite feces, and mite eggs. Scabies can also involve other parts of the body (eg, elbow extensor surfaces, axillary folds). Skin examination usually shows excoriations with small, crusted, red papules scattered around the region. Patients can also develop small vesicles, pustules, or wheals. Linear burrows are the most specific finding in scabies, although they are often obscured by excoriations. Diagnosis is confirmed by skin scrapings from excoriated lesions that show mites, ova, and feces under light microscopy. (Choice A) Budding yeast indicates Candida infection, which most commonly occurs in skin folds with increased moisture and friction. Risk factors include obesity or conditions that interfere with the immune system (eg, diabetes, systemic steroids). Candida intertrigo usually presents with erythematous plaques and erosions with satellite papules or pustules that can occur in the axillae, genital areas, and other skin folds. (Choice B) Molluscum bodies indicate molluscum contagiosum, which is caused by a DNA poxvirus. Patients can develop single or multiple lesions that are smooth, 2-6 mm wide, whitish or skin-colored, and firm, and appear as pearly papules often with central umbilication. However, molluscum contagiosum does not typically involve the palms and soles. (Choice C) Epidermal multinucleated giant cells are seen with herpes simplex and varicella-zoster virus infections. Herpes simplex typically causes vesicular eruptions involving the perioral or genital regions, while varicella-zoster causes a diffuse vesicular rash (primary infection) or more limited dermatomal involvement (eg, shingles). However, this patient's rash distribution (predominantly palms and axilla) is not characteristic of either virus. (Choice D) Necrotic keratinocytes in the epidermis suggest Stevens-Johnson syndrome, a severe reaction that occurs 1-3 weeks after an infection (eg, cytomegalovirus, Mycoplasma) or drug exposure. Patients usually develop high fever, skin pain, mucosal erosions, and skin detachment. However, it typically does not involve the palms and soles. In addition, this patient has no evidence of skin detachment. Educational objective: Scabies is a highly contagious disease that presents with an intensely pruritic rash (usually worse at night) involving the flexor surfaces of the wrist, lateral surfaces and webs of the fingers, elbow extensor surfaces, and axillary folds. Patients usually have excoriations with small, crusted, red papules scattered around the affected areas. Diagnosis is confirmed by skin scrapings from excoriated lesions that show mites, ova, and feces under light microscopy.

A 60-Year-Old Woman Comes to the Physician with 10 Days