Cutaneous lymphoma or benign lesion?

A 66-year-old man presented with an erythematous nodule on the distal ulnar aspect of his forearm, consistent with a pyogenic granuloma on inspection. The lesion had grown in diameter from 5 mm to 30 mm over a few months, was nonulcerated and expressed a small amount of serous fluid (Figure 1A). He reported a 30-year history of similar lesions that had spontaneously resolved. Biopsy results from previous lesions had been consistent with inflamed seborrheic keratosis. Complete excisional biopsy of the current lesion showed a regressing CD30-positive lymphoproliferative disorder with pseudocarcinomatous hyperplasia (Figure 1B). We referred our patient to a lymphoma clinic for staging and treatment. Bone marrow biopsy and computed tomography (CT) of his neck, thorax, abdomen and pelvis were normal. No further treatment was required after the initial surgical excision; however, the patient was advised to return for routine surveillance. A subsequent biopsy of a new lesion showed similar features and lymphomatoid papulosis was diagnosed.

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Figure 1:

(A) Erythematous nodule on the forearm of a 66-year-old man. (B) Photomicrograph of the biopsy specimen showing CD30 positivity in large cells, consistent with lymphomatoid papulosis (original magnification × 200).

Although lymphomatoid papulosis is rare, with an estimated incidence of one to two instances per million,1 the solitary erythematous dome-shaped papules that occasionally characterize it can mimic numerous common skin conditions, including pyogenic granuloma. Lymphomatoid papulosis may also present with multiple lesions, which may be confused with reactions to insect bites and folliculitis.2 These lesions must undergo excisional biopsy for accurate evaluation. Lymphomatoid papulosis is part of a spectrum of CD30-positive lymphoproliferative disorders. It presents as spontaneously regressing papules and nodules that recur over decades. Because lymphoma develops in 10%–19% of patients, regular surveillance is required.3