Background: Commonly described histologic 'clues' to the diagnosis of dermatophytosis include neutrophils in the stratum corneum and/or epidermis, compact orthokeratosis and identification of fungal hyphae between two zones of cornified cells. Prominent (striking) papillary dermal edema (PPDE) is not commonly reported with dermatophytosis (tinea corporis).
Methods: We observed an index case in which PPDE was the salient histologic finding in lesions of tinea corporis. Fifteen additional cases of tinea corporis with PPDE were diagnosed in our dermatopathology laboratory over a 9-year period. The clinical and histologic findings were reviewed.
Results: All 16 cases occurred on the extremities of women, 11 of whom had skin of color. The submitted clinical differential diagnoses varied widely, but included some of the diseases 'classically' associated with PPDE, as well as other blistering eruptions. In several cases, only a few dermatophyte hyphae were identified in tissue sections.
Conclusions: Our case series serves as a reminder that dermatophytosis should be strongly considered in the differential diagnosis of lesions with PPDE. Fungal culture may be helpful in patients whose biopsies show PPDE, negative periodic acid-Schiff (PAS) stains and who fail to respond to conventional anti-inflammatory therapy. This study lends support for the routine use of PAS stains in biopsies of inflammatory dermatoses.