[Misleading bone lesions: When histoplasmosis mimics cancer]

Histoplasmosis is a deep fungal infection caused by the fungus Histoplasma capsulatum. Osseous involvement is relatively rare and is most often associated with Histoplasma capsulatum var. duboisii, sometimes raising diagnostic difficulties in differentiating it from other infectious processes as well as from neoplastic pathology. Here, we present a case of bifocal sacrococcygeal bone histoplasmosis that mimicked a malignant bone tumor on radiological imaging. The patient was a 24-year-old immunocompetent man with a history of an open ballistic fracture of the left leg that occurred a year earlier. He presented with a pseudo tumoral mass on his iliac wing that had spread to his sacrum. Clinical examination revealed an alteration in his general condition. Computed tomography revealed a large, osteolytic, solid-cystic mass centered on the left iliac wing that invaded the sacrum. A surgical biopsy of the iliac mass revealed friable bone with whitish, pasty necrosis. Histological examination of the specimen revealed an epithelioid and giant cell granuloma associated with macrophages. The cytoplasm of multinucleated giant cells contained thick-walled yeasts, highlighted in black by Gomori-Grocott staining. Pathological examination confirmed the diagnosis. The patient was treated with itraconazole. Six months later, the patient's condition had improved, and the lesions appeared to have stabilized. This case highlights the diagnostic challenges of deep fungal infections in settings with limited resources.