A 53-year-old woman comes to the clinic due to a skin rash. For the last 3 weeks, she has had a pruritic rash of worsening severity involving the posterior thighs. The patient recently began an exercise program to lose weight and has been applying a topical analgesic cream to her thighs and buttocks after her workouts. Her past medical history is unremarkable, and she does not use tobacco, alcohol, or illicit drugs. On physical examination, there is an erythematous rash with blisters, ulcers, and weeping drainage involving the posterior thighs bilaterally, as shown in the image below. Which of the following is the most likely finding on skin biopsy?

Question

A 53-year-old woman comes to the clinic due to a skin rash.  For the last 3 weeks, she has had a pruritic rash of worsening severity involving the posterior thighs.  The patient recently began an exercise program to lose weight and has been applying a topical analgesic cream to her thighs and buttocks after her workouts.  Her past medical history is unremarkable, and she does not use tobacco, alcohol, or illicit drugs.  On physical examination, there is an erythematous rash with blisters, ulcers, and weeping drainage involving the posterior thighs bilaterally, as shown in the image below.  Which of the following is the most likely finding on skin biopsy?

Quizplus · Accepted Answer

Eczematous dermatitis (eczema) is a group of conditions characterized by erythematous, papulovesicular, weeping lesions. This patient has acute allergic contact dermatitis (ACD), a form of eczema caused by a type IV (delayed) hypersensitivity reaction to an antigen on the skin surface. In ACD, antigens are taken up by antigen-presenting Langerhans cells and presented to CD4+ T cells in regional lymph nodes. The T cells are activated and migrate to the skin, where they incite an inflammatory response within 24 hours of antigen re-exposure. Acute eczematous dermatitis is characterized histologically by spongiosis, an accumulation of edema fluid in the intercellular spaces of the epidermis. The intercellular bridges become more distinctive in an edematous background, and the epidermis is often described as "spongy." Eventually, the edema can become so marked as to form intraepidermal vesicles. A perivascular infiltrate of lymphocytes and eosinophils may also be seen; this may involve only the superficial dermis (if due to exposure to a surface antigen) or extend to include the deeper vessels (if due to a systemic antigen exposure [eg, drugs]). With persistent antigen exposure, lesions may become less edematous and weepy. Thickening of the stratum spinosum (acanthosis) and stratum corneum (hyperkeratosis) produces raised, scaly plaques(Choices A and D). (Choice B) Dyskeratosis is abnormal, premature keratinization of individual keratinocytes below the stratum granulosum. Dyskeratosis can be due to genetic mutations (dyskeratosis congenita) or may be found in diseases such as squamous cell carcinoma. (Choice C) Hypergranulosis is increased thickness of the stratum granulosum of the epidermis and is seen in conditions such as lichen planus. Educational objective: Acute allergic contact dermatitis is caused by a type IV (delayed) hypersensitivity reaction to an antigen on the skin surface. Gross findings include erythematous, papulovesicular, weeping lesions. Histology is characterized by spongiosis, an accumulation of edema fluid in the intercellular spaces of the epidermis. With chronic exposure, lesions become less edematous, with thickening of the stratum spinosum and stratum corneum.

A 53-Year-Old Woman Comes to the Clinic Due to a Skin