Trichosporon beigelii pneumonia in patients with hematologic malignancies

Trichosporon beigelii is a causative agent of hypersensitivity pneumonia in immunocompetent individuals and of invasive pneumonia in immunocompromised patients. The actual incidence and clinical manifestations of T beigelii pneumonia are obscure because the diagnosis is sometimes difficult. We studied eight patients with T beigelii pneumonia diagnosed by immunohistochemical investigation of lung tissue sections and/or isolation of the organism from the lung, sputum, or blood. All patients had underlying hematologic malignancies for which they had received cytotoxic chemotherapy, resulting in profound neutropenia. The clinical manifestations were persistent fever unresponsive to broad-spectrum antibiotic therapy, cough, bloody sputum, and rapidly progressive dyspnea. The chest radiographs showed diffuse alveolar infiltrates in four patients, diffuse interstitial infiltrates in one, patchy reticulonodular infiltrates in one, and focal alveolar infiltrates in two. Histopathologic examination demonstrated numerous centrally necrotic foci with minimal cellular inflammatory reaction, intra-alveolar hemorrhage, and edema. Trichosporon beigelii consisting of both yeast and hyphal forms was located predominantly in the alveolar vessels. In neutropenic patients with hematologic malignancies, this fungus appears to enter the lung not only through the airways but also via the hematogenous route. In vitro susceptibility testing indicated borderline susceptibility to amphotericin B and showed that some azoles were active against T beigelii at safely achievable serum concentrations.