We report on a 58-year-old woman with long-lasting (36 years) chromomycosis on the foot and secondary self-inoculation from foot to hand 4 years ago. Mycological classification was performed after culture on Sabouraud glucose agar. We used haematoxylin and eosin and Giemsa staining and an antibody to heat shock protein (HSP) 27 (Stress Gen, Clone G3.1) on paraffin-embedded and cryostat specimens of chromomycosis. The mycological culture revealed the fungus Fonsecaea pedosoi. Histopathology revealed dermal fibrosis with persistent fungi (Medlar bodies), numerous mast cells and pseudoepitheliomatous hyperplasia. Immunohistochemically, HSP 27 was positively identified in F. pedrosoi. Moreover, in differentiating keratinocytes in the pseudoepitheliomatous lesions of chromomycosis, HSP 27 was increasingly expressed from basal layers to stratum spinosum in the epidermis but not in keratinocytes directly bordering Medlar bodies. In chromomycosis, HSP 27 is expressed, in accordance with its role as a marker of differentiation and proliferation, in keratinocytes and also in F. pedrosoi. It remains unknown if these results might explain the therapeutic efficacy of hyperthermic treatment.
