Diagnosis: Chronic disseminated histoplasmosis

Discussion

Histoplasmosis also called Darling's disease is caused by a dimorphic fungus Histoplasma capsulatum. ^[1] Histoplasmosis is found throughout the world, but is endemic in the central Eastern part of united states especially, Ohio and lower Mississippi river valleys. ^[2] Several cases have been reported from India, ^[3],[4],[5] although cultural confirmation has been obtained only in some. ^[2] Histoplasmosis may occur in three major clinical forms : Primary cutaneous, pulmonary, and progressive disseminated histoplasmosis. ^[6] Since the onset of the acquired immunodeficiency syndrome pandemic, disseminated histoplasmosis has become a more common opportunistic fungal infection. ^[7] It occurs frequently in HIV-infected persons usually with CD4 counts <75 cells/μl. ^[6] Disseminated histoplasmosis presents a variable clinical picture depending on the degree of parasitization. Acute and sub acute forms present with fever, lymphadenopathy, hepatosplenomegaly, bone marrow depression and adrenal insufficiency. ^[7] Chronic disseminated disease, characterized by low parasitization, occurs almost exclusively in adults and may or may not have systemic sign and symptoms. ^[7] A wide variety of cutaneous lesions including papules, nodules, plaques, ulcers often with annular heaped up borders can be seen in disseminated histoplasmosis. Umblicated papules resembling molluscum contagiosum, erythema nodosum, erythema multiforme, panniculitis, and erythrodermic presentations may also be seen. Oral lesions occurs in about half of all the cases of disseminated histoplasmosis and may be the presenting sign of the disease. Biopsy of a cutaneous or mucosal lesion may be the most rapid way of arriving at the diagnosis as culture may require upto 4-week incubation period ^[7] and may be negative in many cases. ^[4] The diagnostic feature in histology is the presence of tiny 2-4 μm spores within the cytoplasm of macrophages and giant cells.