Granulomatous Panniculitis as a Complication of Subcutaneous Testosterone Pellet Therapy

A 51-year-old man with a 3-year history of exogenous testosterone pellet injections to the left buttock presented for routine skin examination. While the patient reported recurrent drainage from the site of testosterone replacement therapy (TRT) injections, he continued to receive repeated implantations every 6 months. On physical examination, a 12-mm irregular, brown macule was identified within a poorly demarcated, ecchymotic, and fluctuant subcutaneous plaque on the left buttock with a sinus tract draining serosanguinous fluid. The pigmented lesion was biopsied, revealing malignant melanoma in situ; hence, a wide local excision was scheduled. During the procedure, necrotic subcutaneous fat was observed surrounding the site of biopsy, and a region measuring 18 cm² approximately was debrided and submitted for pathologic evaluation. Histopathologic examination revealed a diffused subcutaneous granulomatous infiltrate with septal and lobular panniculitis and fat necrosis as well as peripherally palisading histiocytes and hemosiderin deposition (Figures 1A and B). Similar findings were observed in another specimen from the same segment of debrided tissue, compatible with granulomatous panniculitis. Periodic acid-Schiff (PAS), Gram's, and acid-fast bacilli (AFB) stains revealed no microorganisms. During surgical exploration, six foreign bodies were discovered and identified as undissolved testosterone pellets. The patient was referred to a wound care center, but ultimately lost to follow-up.