PHEOHYPHOMYCOSIS DUE TO ALTERNARIA SPP AND PHAEOSCLERA DEMATIOIDES - A HISTOPATHOLOGICAL STUDY

A case of phaeohyphomycosis caused by strains of both Alternaria spp. and Phaeosclera dematioides is presented. The biopsy material was stud ied using histological, immunohistochemical and transmission electron microscopy techniques. The agent's dematiaceous mycelia are composed o f thick-walled hyphae, branched and unbranched, with terminal vesicula r formations. All the described structures occur alone or in chains wi thin multinuclear giant foreign body-type cells or invading an abscess . Also present are budding forms. Immunostaining of histiocytic inflam matory cells in either diffuse or granulomatous infiltrates revealed c ytoplasmic positivity for lysozyme and Ki-M1P antibody. The lymphocyti c infiltrates of the upper cerium show predominantly small T lymphocyt es (CD3 and CD45RO positive) and absence of CD20-positive B cells. Pla sma cells occurring within the infiltrates of the deeper parts show po lyclonal expression of both Ig light-chains.