Unusual fungal infection Unusual skin infection Unusual fungal skin infection An increased susceptibility to fungal infection of the skin or subcutaneous tissue, as manifested by a recurrent, severe, or atypically distributed fungal lesion, or by an infection caused by an atypical or opportunistic organism. Common manifestations include chronic mucocutaneous candidiasis or subcutaneous mycoses (such as sporotrichosis caused by Sporothrix species. An unusual fungal skin infection is a hallmark of T-cell deficiencies, inborn errors of IL-17 immunity (e.g., STAT1 gain-of-function, AIRE deficiency), and CARD9 deficiency, which specifically predisposes to deep dermatophytosis and subcutaneous fungal invasion.