Histoplasma Infection in a Case of Multiple Myeloma Presenting as a Diagnostic Conundrum

Abstract

Histoplasma is a common dimorphic fungus in the environ-ment. Infection by this fungus in an immunocompetent host might present with fl u-like symptoms or might be innocu-ous. However, in immunocompromised host, itcan cause any of the clinical subtypes: pulmonary, disseminated, or systemic disease. 1 Here we present a case of a patient of multiple myeloma who developed disseminated histoplasmosis post allogenic bone marrow transplant. A 45-year-old gentleman, a known case of pulmonary tuberculosis, who presented with back pain. The patient had taken complete course of ATT. Bone marrow examination showed80%plasmacells.Electrophoresisshowedthepresence of the M band, which was proven to be IgG kappa subtype by immuno fi xation studies. Serum-free light chain ratio was deranged. The patient received induction chemotherapy with bortezomib,lenalidomide,anddexamethasone;however,itdid not achieve complete remission, hence he was advised for autologous stem cell transplant. He underwent stem cell trans-plant,andwasonlenalidomidetherapyfor8months.However, his condition relapsed in 10 months and he was started on pomalidomide4mg withdexamethasonefor 6cycles,followed by single agent pomalidomide 2mg and was on follow-up. Presently, 3.5 years post-transplant, the patient came with persisting thrombocytopenia. Bone marrow showed hypercellular marrow and trephine biopsy showed single granuloma consisting of a few histiocytes with a single giant cell. PAS and GMS staining