The intricate relationship of histoplasmosis and sarcoidosis: a case report

Histoplasmosis is an endemic mycosis with most cases of clinical illness reported in North and Central America. Rarely, patients develop progressive disseminated histoplasmosis with extrapulmonary manifestations. These infections are fatal if not appropriately treated.

We report a case of progressive disseminated histoplasmosis presenting with fever, progressive dyspnea, and pancytopenia in a 51-year-old Caucasian man who had been treated with chronic steroids for a diagnosis of sarcoidosis made 20 years previously. His presentation was initially mistaken for sarcoidosis but, fortunately, laboratory results showed hematologic abnormalities, and the diagnosis of histoplasmosis was made by bone marrow biopsy.

Sarcoidosis reduces T cell activity, and the addition of steroids for treatment causes further immunosuppression and vulnerability for development of a disseminated infection. The diagnosis of histoplasmosis depends mainly on clinical presentation and host factors. Although there are diagnostic laboratory tests available, clinicians may need to diagnose histoplasmosis by history and physical examination alone and treat empirically, since awaiting Histoplasma-specific laboratory results would delay initiation of treatment. Primary care providers, hospitalists, and subspecialists alike should be aware of the overlap in clinical and radiological presentations of sarcoidosis and histoplasmosis, and when and how to pursue diagnostic testing for endemic mycoses, since these infections can be fatal in immunosuppressed patients without appropriate treatment.