Oral Histoplasmosis in an Immunocompetent Male Diagnosed by Culture, Histopathology, and MetaCAP

Histoplasmosis is a systemic fungal infection caused by the dimorphic fungus Histoplasma capsulatum, commonly found in soil contaminated by bird or bat excrement. Oral granulomatous histoplasmosis is a relatively rare presentation that often lacks typical clinical features. Patients may experience persistent oral pain or lesions lasting several weeks, and clinical presentations can mimic malignant tumors or other infectious pathogens, leading to diagnostic challenges.

We report a case of oral granulomatous histoplasmosis in a 53-year-old immunocompetent male, initially suspected of having lymphoma or tuberculosis. To our knowledge, this is an exceptional case of oral histoplasmosis diagnosed in an immunocompetent patient through a combination of tissue fungal culture, pathological biopsy, and metagenomic capture sequencing (metaCAP).

The case highlights the importance of considering fungal infections in persistent oral lesions of immunocompetent patients. It also demonstrates that metaCAP, alongside conventional culture and histopathology, can facilitate a definitive diagnosis in challenging cases.