Endovascular Infections Caused by Histoplasma capsulatum: A Case Series and Review of the Literature

Abstract

Context.—Endovascular infection is an uncommon but devastating manifestation of histoplasmosis, which is often diagnosed late in disease. Objectives.—To evaluate the clinical and pathologic characteristics of patients with endovascular infections caused by Histoplasma capsulatum. Design.—All cases of patients with documented endovascular histoplasmosis at a single tertiary care center in an endemic region during the period 1993–2010 were reviewed. Results.—Patients presented with a subacute febrile illness and a history of endovascular devices. All patients had positive Histoplasma serology. Routine bacterial culture results were negative for all patients. In addition to yeast forms typical of histoplasmosis, pathologic findings also revealed mycelial forms in 4 of 5 patients. Inflammation was scant. Urinary antigen detection was positive in 4 of 5 patients and Histoplasma blood culture results were positive for 3 of 5 patients. Four patients were treated with a combination of surgical and medical therapy, which consisted of amphotericin B followed by itraconazole; these 4 patients had complete resolution of symptoms and no documented relapse. One patient died before planned surgery. Conclusions.—Histoplasma capsulatum endovascular infections are clinically characterized by a subacute febrile illness with negative bacterial cultures in patients with prosthetic endografts or valves. Noninvasive diagnostics are often the initial clue to the diagnosis. Combined medical and surgical treatment is associated with survival. On histopathologic examination both mycelial and yeast forms are often observed, with absent to minimal tissue inflammatory reaction.