Introduction: Histoplasmosis is a tropical fungal infection sharing many similarities with tuberculosis: the transmission by air dropplets, the usually asymptomatic primary-infection, the disseminated infection encountered among immunosuppressed patients and the granulomatous pathological lesions. In France, histoplasmosis is uncommon and may be misdiagnosed as tuberculosis.
Observation: A 78 years old male patient presents with a raspberry-like lesion of the mouth causing difficulties to eat and weight loss of 14 kg. The diagnosis of tuberculosis is evoked because of the presence of a giant-cell granuloma in one of the biopsies. The histoplasmosis serology, requested because the patient stayed in Africa, is positive. Revisions of the pathology put into evidence the presence of spores in histiocytes confirming diagnosis of histoplasmosis. The treatment with itraconazole is effective.
Conclusion: Histoplasmosis is a differential diagnosis of tuberculosis, especially in endemic regions. The histoplasmosis serology can be useful. The reference in diagnosis examinations keeps being the microscopic observation of spores and their mycological growth.