Invasive infection with Fusarium chlamydosporum in a patient with aplastic anemia

Abstract

We report the first case of invasive disease caused by Fusarium chlamydosporum. The patient had aplastic anemia with prolonged neutropenia and was treated with immunosuppressive therapy. While she was receiving empirical amphotericin B, a dark crusted lesion developed on her nasal turbinate. Histologic analysis revealed invasive hyaline hyphae and some darkly pigmented structures that resembled conidia of dematiaceous molds. Only after the mold was grown in culture were characteristic colonial morphology, phialides, conidia, and chlamydospores evident, thus permitting the identification of F. chlamydosporum. This case illustrates the ever-increasing spectrum of pathogenic Fusarium spp. in immunocompromised patients and emphasizes the potential pitfalls in histologic diagnosis, which may have important treatment implications.

FIG. 1

F. chlamydosporum grown on cornmeal agar (magnification, ×1,200). (A) Conidiophores with sympodially proliferating phialides and microconidia; (B) a fusiform macroconidium with four cells and a microconidium with two cells; (C and D) chlamydospores.

FIG. 2

In vivo morphology of F. chlamydosporum (magnification, ×1,200). (A) Dark-walled chlamydospores seen in the hematoxylin and eosin-stained section; (B) muriform chlamydospore (Gomori methenamine-silver stained); (C) septate hyphae (Gomori methenamine-silver stained).