A 28-year-old man comes to the office with bilateral skin lesions over the posterior surface of the elbows. The lesions are itchy at times; topical moisturizers have reduced the itching, but the lesions have remained. The patient has no chronic medical problems and takes no medications. Biopsy of the lesions demonstrates hyperkeratosis, parakeratosis, dilated capillaries in the dermal papillae, and foci of neutrophils in the superficial epidermis. Which of the following is the most likely diagnosis?

Question

A 28-year-old man comes to the office with bilateral skin lesions over the posterior surface of the elbows.  The lesions are itchy at times; topical moisturizers have reduced the itching, but the lesions have remained.  The patient has no chronic medical problems and takes no medications.  Biopsy of the lesions demonstrates hyperkeratosis, parakeratosis, dilated capillaries in the dermal papillae, and foci of neutrophils in the superficial epidermis.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec160b_3901_e73b_9249_61dde2fb7217_MD0001_00 Psoriasis is a common chronic inflammatory skin disorder that presents with scaly, erythematous plaques, typically on the extensor surfaces of the elbows and knees. In predisposed individuals, disruption of the epithelial barrier leads to activation of antigen-presenting dendritic cells and subsequently to a self-reinforcing inflammatory cascade characterized by recruitment and activation of T helper cells and proliferation of keratinocytes. Histopathologically, psoriasis is characterized by: In addition, the epidermal cell layer superficial to the dermal papillae may be thinned and contain dilated blood vessels, which leads to pinpoint bleeding when the scale is removed from the plaque (Auspitz sign). (Choice A) Chronic atopic dermatitis can produce plaques characterized by hyperkeratosis and acanthosis, often with a lymphocytic or eosinophilic infiltrate. However, adults most commonly develop lesions on flexural surfaces (eg, anterior elbows), and most patients have a history of other atopic disorders (eg, asthma, allergic rhinitis) beginning in childhood. (Choice B) Dermatitis herpetiformis presents with erythematous, pruritic papules, vesicles, and bullae symmetrically on the elbows, knees, upper back, and buttocks. It is strongly associated with celiac disease, and histopathology shows microabscesses at the dermal papillary tips, which coalesce to form subepidermal blisters. (Choice C) Erythema nodosum is characterized by painful, red nodules on the shins and often represents an inflammatory response to medications (eg, oral contraceptives), infections, inflammatory bowel disease, or sarcoidosis. Histopathology is variable but typically shows a septal panniculitis with a mixed cellular infiltrate. (Choice E) Urticaria ("hives") is a transient dermatologic disorder that is caused by antigen-induced degranulation of focal mast cells through IgE antibody sensitization. This degranulation causes microvasculature hyperpermeability and the formation of wheals that typically surface and resolve within hours. Educational objective: Psoriasis is characterized by hyperkeratosis and confluent parakeratosis of the stratum corneum, and epidermal hyperplasia (acanthosis) with elongated rete ridges. Neutrophilic foci in the stratum corneum and epidermis may coalesce to form microabscesses (Munro microabscesses).

A 28-Year-Old Man Comes to the Office with Bilateral Skin