Cutaneous and subcutaneous phaeohyphomycosis caused by Exserohilum rostratum

Abstract

Phaeohyphomycosis of the skin caused by Exserohilum is rare. Four cases have been reported; all were subcutaneous in type and all were caused by Exserohilum rostratum. We report two types of skin infection, cutaneous and subcutaneous, that were caused by E. rostratum in two immunocompromised men. Pleomorphic fungal elements were noted within the dermal suppurative and granulomatous infiltrate in case 1 and only within the central hyperkeratotic horny layer of a porokeratosis-like lesion in case 2. E. rostratum was isolated in both cases. Case 2 represents the first documented case of cutaneous Exserohilum phaeohyphomycosis. The clinical and histologic features in this case resembled superficial porokeratosis. To the best of our knowledge these findings have not been reported previously in fungal infections of the skin. The ambiguous terminology that is used in the classification of phaeohyphomycosis is also discussed.