New clinical phenotypes of fungal infections in special hosts

Incidence of invasive fungal infections increases over time with the rise in at-risk populations; in particular, patients with acquired immunodeficiencies due to immunosuppressive therapies such as anti-tumour necrosis factor-α (TNF-α) treatment, cirrhosis or burns. Some primary immunodeficiencies (PID) can also predispose selectively to invasive fungal diseases. Conversely, some atypical fungal diseases can reveal new PID. Deep dermatophytosis, Candida central nervous system infections or gastrointestinal disease, or disseminated phaeohyphomycosis-revealed CARD9 deficiency. Most patients with inherited chronic mucocutaneous candidiasis were found to carry STAT1 gain-of-function mutations. The spectrum of fungal susceptibility and clinical presentation varies according to the PID. Among acquired immunodeficiencies, immunosuppressive treatments such as TNF-α blocker therapy, which has revolutionized autoimmune disorder treatment, may be complicated by endemic mycosis, aspergillosis, pneumocystosis or cryptococcosis. Burn patients with damaged skin barrier protection are susceptible to severe Candida infections and filamentous fungal infections (such as Aspergillus spp., Mucorales). Moreover, patients with cirrhosis are at increased risk of fungal infections. Therefore, physicians should think of any potential underlying acquired or inherited immunodeficiency in a patient developing an atypical fungal infection, or of a potential fungal disease in the context of an atypical presentation in specific hosts.