Cutaneous Histoplasmosis in HIV Seronegative Patients: A Clinicopathological Analysis.

Background: Diagnosis of extrapulmonary histoplasmosis in HIV seronegative and immunocompetent patients is often challenging, so a high index of suspicion is required. Cutaneous manifestation of infection shows a wide spectrum of lesions including erythematous plaques; maculopapules; crusted, verrucous, or desquamative papules and nodules; abscesses; and mucocutaneous ulcers among others. Due to the variations in its clinical presentation, histopathology plays a very important role in the detection of spores and the confirmation of diagnosis.

Objective: The aim of our study was to analyze clinicopathological characteristics of cutaneous manifestations of biopsy-proven histoplasmosis in HIV seronegative individuals. We also examined the utility of Fite stain for the diagnosis of Histoplasma capsulatum on tissue biopsy sections.

Methods: This was a retrospective, observational study on 7 patients who were HIV seronegative and clinically manifested with isolated cutaneous lesions or disseminated disease. Skin biopsy from the lesions was performed on all 7 patients. In addition to H&E staining and special stains for detecting fungus, Fite staining was performed on all of the cases to study its utility in detecting H. capsulatum spores.

Results: The skin lesions were widely disseminated in all patients and the most common cutaneous lesions were papules, present in all 7 patients. On review of the H&E-stained slides, the most common pattern was histiocytic lobular panniculitis-like infiltrate observed in 4 cases. Fite stain highlighted the yeast as magenta-colored spores on a blue background in all cases, except for 1 with a granulomatous pattern.

Conclusions: A primary cutaneous manifestation of H. capsulatum infection in non-HIV-infected individuals is extremely rare. Fite stain could aid in differentiating the spores of H. capsulatum from those of other fungi, Cryptococcus and Candida in particular.