Fungus – Phaeohyphomycosis
Phaehyphomycosis is a group of dematiaceous fungal infections which I encounter in my The Woodlands dermatology and Conroe dermatology offices. Dematiaceous fungi all produce pigmented hyphae as they are capable of producing melanin. Phaehyphomycosis infections may be superficial in which only the stratum corneum is involved as in Tinea nigra. Tinea nigra is caused by Phaeoannellomyces werneckii, which is found in hot humid environments. In the United States, Tinea nigra is most commonly found along the Gulf coast. Clinically, Tinea nigra appears as small brown/black macules on the palms and soles and may be mistaken for moles. Diagnosis can be made through KOH scrapings of the scale and Tinea nigra is easily treated with topical clotrimazole cream twice a day. Alternariosisis another Phaeohyphomycosis infection that can appear similar to Tinea nigra in immunocompetent patients. Direct inoculation of Phaeohyphomycotic organisms into the skin can produce subcutaneous cysts, which may have to be excised. Disseminated Phaeohyphomycosis occurs in immunocompromised patients and the skin lesions arising from dissemination appear as black escharotic plaques. Treatment of disseminated Phaeohyphomycotic infections usually requires oral Itraconazole daily for several months.