Needles in a haystack: Extremely rare invasive fungal infections reported in FungiScope^Ⓡ—Global Registry for Emerging Fungal Infections

Objectives: Emerging invasive fungal infections (IFI) have become a notable challenge. Apart from the more frequently described fusariosis, lomentosporiosis, mucormycosis, scedosporiosis, and certain dematiaceae or yeasts, little is known about extremely rare IFI. Methods: Extremely rare IFI collected in the FungiScope^Ⓡ registry were grouped as Dematiaceae, Hypocreales, Saccharomycetales, Eurotiales, Dermatomycetes, Agaricales, and Mucorales. Results: Between 2003 and June 2019, 186 extremely rare IFI were documented in FungiScope^Ⓡ. Dematiaceae (35.5%), Hypocreales (23.1%), Mucorales (11.8%), and Saccharomycetales (11.3%) caused most IFI. Most patients had an underlying malignancy (38.7%) with acute leukemia accounting for 50% of cancers. Dissemination was observed in 26.9% of the patients. Complete or partial clinical response rate was 68.3%, being highest in Eurotiales (82.4%) and in Agaricales (80.0%). Overall mortality rate was 29.3%, ranging from 11.8% in Eurotiales to 50.0% in Mucorales. Conclusions: Physicians are confronted with a complex variety of fungal pathogens, for which treatment recommendations are lacking and successful outcome might be incidental. Through an international consortium of physicians and scientists, these cases of extremely rare IFI can be collected to further investigate their epidemiology and eventually identify effective treatment regimens.