[American histoplasmosis: clinicopathological features in immunocompetent and immunocompromised patients. A report of two cases of infection by Histoplasma capsulatum on Reunion Island]

Abstract

Introduction: Histoplasmosis is a fungal infection caused by Histoplasma capsulatum var. capsulatum. It shows pulmonary or multivisceral involvement. Infective spores are inhaled from soils that contain bat or bird guano. The clinical picture depends on the intensity of the exposure and the immune status of the host.

Case reports: We report two cases of histoplasmosis that reflect its variability in clinical and histopathological expression: a pseudo-tumoral nodular form or histoplasmoma in a pauci-symptomatic immunocompetent patient and a disseminated form with severe respiratory and mucocutaneous involvement in an immunocompromised patient. The histoplasmoma presented as a spiculated, hypermetabolic, solitary pulmonary nodule. Histopathological examination showed well-formed epithelioid granulomas with caseous central necrosis containing numerous histoplasma yeasts. In the patient with disseminated infection, the diagnosis was confirmed by seeing yeast forms in bronchoalveolar lavage fluid and skin biopsy.

Conclusions: These patients are the second and third cases of histoplasmosis reported on Reunion Island. Both had traveled in endemic areas several years previously. The most likely pathophysiological mechanism is the reactivation of an old latent infection. There is, therefore, no argument at present in favor of the presence of contaminated soils on Reunion Island.

Keywords: Granuloma; Granulome; Histoplasma capsulatum; Histoplasmose; Histoplasmosis; La Réunion; Lung; Poumon; Reunion Island.