Disseminated Histoplasmosis in an Adult With Rheumatoid Arthritis Not on Biological Immune Modulators

Histoplasmosis is a fungal disease caused by a dimorphic fungus known as Histoplasma capsulatum (H. capsulatum), which is endemic to areas around river valleys and southeastern states in the United States (US). Patients with histoplasmosis are asymptomatic, and the condition is usually diagnosed by an incidental finding of a pulmonary granuloma on a chest radiograph. In rare cases, this disease can develop into a progressive disseminated form and cause fatal and diffuse pulmonary infiltrates in immunocompromised adults. Moreover, there is a close association between disseminated histoplasmosis and the use of tumor necrosis factor (TNF) inhibitors in rheumatoid arthritis (RA). Our case report discusses a unique presentation of disseminated histoplasmosis in a patient with RA who was not on any biological immune modulators. The disseminated histoplasmosis in this case was progressive and involved the central nervous system, liver, lungs, and oral mucosa and was treated successfully with amphotericin therapy. We also discuss the disease process in detail and hypothesize that RA could be an independent risk factor for the increased incidence of disseminated histoplasmosis in adults. Based on the findings in this case report, we recommend screening for latent Histoplasma infections in adults with RA living in endemic areas and keeping a low threshold to evaluate flare-ups from this disease regardless of the use of anti-TNF inhibitors. Specific experimental and epidemiological studies can be conducted to examine the association between RA and similar indolent fungal infections.