Tropical Pyomyositis in a Patient From St. Croix

A 70-year-old man living in St. Croix, developed persistent swelling of his right leg approximately 1 year after undergoing pelvic lymph node dissection and irradiation in the United States for locally invasive adenocarcinoma of the prostate. Approximately 1 month prior to admission, he had noticed slow, painful swelling of his right groin associated with erythema and increased warmth. He reported no history of trauma. A computed tomography (CT) scan demonstrated an intramuscular soft tissue mass in the right iliopsoas, obturator, and adductor magnus muscles. A 19-day course of corticosteroids provided symptomatic improvement; however, cessation of this medication resulted in the rapid return and distal extension of the swelling. In addition, edema and a firm, "woody" mass developed in the lateral aspect of the right thigh, although there were no constitutional symptoms. Because of the recrudescence of symptoms, the patient was again placed on corticosteroids. After noting no improvement in 48 hours, the patient sought treatment in the United States, where he was diagnosed with tropical pyomyositis. Imaging studies demonstrated copious purulent material distributed in and between the anterior femoral muscles (Fig. 1). Culture of the pus drained intraoperatively yielded Streptococcus anginosus and Bacteroides vulgaris. The patient recovered after repeated surgical drainage and treatment with intravenous penicillin and metronidazole.