Disseminated Histoplasmosis Presenting as an Isolated Oral Ulcer in a 91-Year-Old Patient Without Recognized Immunodeficiency: A Case Report.

Disseminated histoplasmosis is commonly seen in immunocompromised individuals with acquired immune deficiency syndrome (AIDS). It is relatively uncommon in individuals without recognized immunodeficiency and typically affects older men. We present a case of a 91-year-old male with no apparent immune deficiency disorder and having a remote history of occupational exposure to chicken houses who presented with an isolated, painful left buccal cavity ulcer, which was initially diagnosed as an aphthous ulcer. After six weeks of progressive symptoms and poor nutritional intake, the biopsy of the ulcer revealed mucocutaneous histoplasmosis. During that time, the patient also developed cytopenias, predominantly leukopenia and thrombocytopenia. Abdominal imaging revealed bilateral adrenal masses. Bone marrow biopsy, as well as adrenal biopsy and culture, were consistent with disseminated histoplasmosis. Due to extreme frailty and poor nutritional intake, amphotericin B was deferred. Administration of itraconazole also became challenging due to severe oral ulcer pain, and eventually, a percutaneous endoscopic gastrostomy (PEG) tube was placed. Despite adequate antifungal therapy via PEG tube, the patient continued to remain extremely frail and ultimately died after transitioning to hospice care within one week of diagnosis of disseminated histoplasmosis. This case illustrates how an isolated oral ulcer can be the initial and dominant clinical manifestation of widespread disseminated histoplasmosis likely related to underlying immunosenescence. It also highlights a critical gap in the treatment guidelines for disseminated histoplasmosis in an extremely elderly and frail population.