Emerging subcutaneous mycoses by opportunistic filamentous fungi: A retrospective study in Northwest Spain.

Background: Subcutaneous mycoses caused by opportunistic filamentous fungi are emerging infections in developed countries due to the longer survival of immunocompromised patients. The evidence published in relation to subcutaneous mycoses is fundamentally based on case reports and small case series.

Methods: We performed an observational retrospective study of subcutaneous mycoses caused by opportunistic filamentous fungi diagnosed at our institution between 2017 and 2022. This study aims to estimate the incidence rate of subcutaneous mycoses, identify which fungal species are involved, and analyse which clinical variables predispose to infection and if any are associated with mortality.

Results: Fifteen patients met the inclusion criteria. The median age was 61 years (range 27-84), and 80% of them were males. Alternaria spp. were the most common fungi. Two other organisms were frequently isolated: Scedosporium apiospermum and Fusarium solani. Among patients infected with F. solani, 66.7% died. The most common clinical presentation was suppurative nodules in the lower limbs and the main risk factors for infection were immunosuppressants, corticosteroids, previous trauma and transplantation, but they were not particularly associated with increased mortality. A statistically significant association with mortality was only found in the case of positive blood culture (p = <.001).

Conclusions: Phaeohyphomycosis has a lower risk of dissemination, especially when compared to subcutaneous mycoses caused by hyalohyphomycetes. It is important to convey the severity of these skin infections to the physicians involved in the treatment and follow-up of susceptible patients to avoid misdiagnosis and delays in the treatment, especially in the case of hyalohyphomycosis.