Photo Quiz: Fungal sinusitis in a 75-year-old neutropenic cancer patient.

Diagnosis: Invasive fungal sinusitis due to Curvularia species. This patient described had a prolonged neutropenia, with upper respiratory symptoms and sinus mucosal thickening. Aspergillosis and mucormycosis are common causes of fungal sinusitis in this immunocompromised population, but Curvularia and other dematiaceous molds (DMs) can occur less frequently. Curvularia has been known to cause sinonasal, pulmonary, skin, and intracranial infections, keratitis, and disseminated disease in the immunocompromised host [1, 2]. DMs are ubiquitous organisms, with >150 species and 70 genera [3]. The distinguishing characteristic common to these diverse species is the presence of melanin in their cell walls. Other DMs commonly associated with clinical syndromes of phaeohyphomycosis include Bipolaris and Exserohilum, among others, and are classified according to conidia/conidiophore morphology [2].Multiple species of Curvularia have been implicated in human disease with recent molecular typing identifying several new species [4]; however, C. lunata is the most commonly reported clinical species [3]. In the laboratory, colonies grow rapidly on potato dextrose agar, developing the characteristic grayish-black appearance. DMs do not have characteristic growth on Sabouraud dextrose agar, a common primary fungal media [2].Tape mount with lactophenol cotton blue of a colony (Figure 1) revealed characteristic curved macroconidia with transverse septae and an enlarged darker central cell causing the bent appearance (left arrow). In the background, septate hyphae are visible as well (right arrow). Darkly pigmented, bent, or knobby (sympodial Figure 2. Histopathology of anterior aspect of middle turbinate. A, Hematoxylin–eosin stain (×1000 magnification with oil). B, Grocott methenamine silver stain (×200 magnification). The dark brown melanin pigment in the cell wall of the hyphae (arrows). Figure 1. Tape mount with lactophenol cotton blue of mold colonies showing curved macroconidia and septate hyphae. Characteristic curved macroconidia with transverse septae and an enlarged darker central cell causing the bent appearance (left arrow). In the background, septate hyphae are visible as well (right arrow).