Photo Rounds

Erythema on abdomen

A 17-year-old woman presented to her family physician (FP) with a large area of erythema on her left lower abdomen of 5 days’ duration. She denied fever but reported tenderness at the site. She was given a 7-day course of cephalexin, but at her follow-up visit a week later, it appeared that an abscess had formed. The FP performed an incision and drainage (without much purulence drained). The patient was given 1 week of oral trimethoprim-sulfamethoxazole to treat the remaining erythema around the lesion. At the 1-week follow-up, the site remained erythematous, purulent, and tender; the patient was afebrile. There appeared to be an ulcer at the site of the incision and drainage.

What’s your diagnosis?


Erythema on abdomen

The FP was puzzled by the lack of response to treatment and decided to perform a 4-mm punch biopsy at the edge of the nonhealing ulcer. (Note that the correct location for a biopsy of an ulcer is on the edge, not in the middle). His differential diagnosis included pyoderma gangrenosum and a deep fungal infection. The pathologist called a week later FP with a surprising result: anaplastic large cell cutaneous T-cell lymphoma. (See the Watch & Learn video on “Punch biopsy.”)

Anaplastic large cell cutaneous T-cell lymphoma is a rare diagnosis—especially in a teenager—and it can’t be determined by appearance only. On follow-up, the FP explained the diagnosis to the patient and her mother. He called Hematology/Oncology to facilitate the referral.

The patient was treated by the specialist with weekly oral methotrexate and her skin cleared up completely. Although she would likely need treatment for years, the prognosis was good. This case is a reminder that when a treatment is not working for an expected diagnosis, it’s time to reconsider the diagnosis and do further testing to identify the correct diagnosis.

Photos and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Chacon G, Nayar A, Usatine R, Smith M. Cutaneous T-cell lymphoma. In: Usatine R, Smith M, Mayeaux EJ, et al. Color Atlas and Synopsis of Family Medicine. 3rd ed. New York, NY: McGraw-Hill; 2019:1124-1131.

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