Phellinus species: An emerging cause of refractory fungal infections in patients with X-linked chronic granulomatous disease

Aspergillus spp. are a leading cause of mortality in chronic granulomatous disease (CGD), but other fungi have emerged in the era of mould prophylaxis. Of these, Phellinus spp. are an under-recognised cause of invasive fungal infections (IFIs) in CGD, and data on their presentation and management are scarce. We present a patient with CGD who developed disseminated IFI involving the lungs and brain. Surgical specimens grew a basidiomycete which was disregarded as a contaminant. After three months of progressive disease despite antifungals, he was diagnosed with Phellinus tropicalis by internal transcribed spacer (ITS) sequencing. He improved with amphotericin B and isavuconazole but required haematopoietic stem cell transplantation (HSCT). We review the literature on Phellinus infections in CGD and conclude that: (i) these infections emerge on mould-active prophylaxis and are indolent; (ii) they typically cause locally destructive disease but can disseminate; (iii) diagnosis is delayed and requires molecular methods; (iv) amphotericin B is most active in vitro; and (v) treatment is protracted and requires surgery and possibly HSCT. In conclusion, Phellinus spp. are emerging pathogens in CGD. Every effort should be made to establish the diagnosis of non-Aspergillus IFIs in patients with CGD by sending tissue specimens for molecular diagnostics.