Disseminated Histoplasmosis: A Rare Cause of Pancytopenia in an Immunocompromised Patient

Histoplasma capsulatum is a dimorphic fungus endemic to North and South America. This organism's ubiquity outside the traditionally defined region of the Mississippi and Ohio River Valley makes it an important yet often forgotten cause of systemic inflammatory disease. Progressive disseminated histoplasmosis is an uncommon opportunistic infection, largely affecting immunocompromised individuals with defects in T-cell immunity. The initial manifestations of disseminated histoplasmosis present non-specifically with symptoms such as fever, malaise, anorexia, and weight loss. Given this fungi's endemic nature, disseminated histoplasmosis is an essential disease for physicians to diagnose accurately. Diagnosis can be established through antigen detection in the blood or urine, although the gold standard is tissue diagnosis or fungal culture. Treatment of mild to moderate disease consists of an itraconazole regimen for a year, yet severe disease requires an additional 14-day induction therapy with amphotericin B. We present a case of disseminated histoplasmosis in a breast cancer patient, recently treated with neoadjuvant chemotherapy, who presented with new-onset pancytopenia.