Immunohistochemical study of subcutaneous phaeohyphomycoses.

Immunohistochemical study of inflammatory infiltrate was carried out in five cases of subcutaneous phaeohyphomycosis before and after therapy. The infections were due to the genus Alternaria in four cases and genus Cladosporium in one. In four cases, infiltrating T cells with helper memory phenotype were slightly more abundant after therapy (70-80% versus 75-90% of T lymphocytes) and those with suppressor cytotoxic phenotype were slightly less abundant (20-25% versus 10-15%). In one case, CD8+, Tia-1+ lymphocytes constituted 50% of the T-cell infiltrate before and after therapy. In all cases, the infiltrate contained many CD79 a+ plasma cells, which increased slightly after therapy, and a high CD1a positivity of dendritic cells (presumably Langerhans cells) before and after therapy. The CD1a+ cells were detected in the epidermis and in granulomatous infiltrate; in the dermis and subcutis, many were close to fungal structures. In four cases, intra-epidermal CD1a+ cell number was slightly lower than in control skin. CD68+ cells were not found in the epidermis.