Primary soft-tissue nocardiosis.

A 20-year-old Latin American man presented with a 4 1/2-year history of a left infrapatellar mass with multiple draining sinuses. Multiple courses of oral antibiotics before referral were unsuccessful in eradicating the mass. Microscopic examination of material obtained by punch, core needle, and incisional biopsies demonstrated nonspecific acute and chronic inflammation. Surgical resection demonstrated an inflammatory mass with multiple abscess cavities. Intraoperative cultures grew Nocardia asteroides. The infection was successfully treated with a prolonged course of a trimethoprim-sulfamethoxazole.