Rare Case Report of Histoplasmosis Osteomyelitis in Immunocompetent Adult

Histoplasma capsulatum is a thermally dimorphic fungus that is endemic to North and Central America and rarely encountered in Asia. Musculoskeletal involvement is uncommon, particularly in immunocompetent individuals. This report presents a rare case of localized histoplasmosis osteomyelitis involving two skeletal sites in an immunocompetent patient.

A 53-year-old immunocompetent female presented with a 6-month history of chronic, multifocal osteomyelitis involving the right lateral malleolus and left ring finger. She had no systemic symptoms or history suggestive of immunosuppression. Radiographs revealed osteolytic lesions, and histopathological examination demonstrated granulomatous inflammation with fungal spores confirmed by periodic acid-Schiff and Gomori Methenamine Silvers staining, consistent with H. capsulatum. The patient underwent surgical debridement with autologous cancellous bone grafting and temporary external fixation. Post-operatively, she received intravenous Amphotericin B for 6 weeks, followed by a period of protected mobilization. At 1-year follow-up, the patient had complete recovery with no evidence of recurrence.

Localized histoplasmosis osteomyelitis in an immunocompetent host is extremely rare and may mimic bacterial osteomyelitis. A high index of suspicion, timely histopathological diagnosis, and appropriate antifungal therapy combined with surgical management are essential for optimal outcomes.