Cell-matrix patterns in the cutaneous lesion of chromomycosis

Chromomycosis is a chronic fungal infection characterized by dermal fibrosis with persisting fungi in situ, generally leading to a verrucous skin lesion. The absence of good clinical results under specific treatment suggests irreversibility of the fibrotic lesion. Frozen and paraffin-embedded skin biopsies of eleven patients with chromomycosis due to Phialophora pedrosoi were studied by immunohistochemistry and electron microscopy. Distinct cell-matrix patterns were found in different tissue localizations: neutrophilic abscesses with oedema and necrotic keratinocytes in the epidermis; dense connective matrix around inflammatory infiltrates, mainly composed of macrophages and giant cells, and organized granuloma in the dermis. Active fibroblasts and mast cells were constantly observed. The inability of fibrotic tissue to be remodelled seems correlated to the nature and the organization of the matrix components but, the factors triggering the initial fibrogenic events remain to be characterized.