[Neurothekeoma. A light and electron microscopy, histochemical and immunohistochemical study].

We report a 37-year-old man with neurothekeoma that developed on the tip of the nose. Histopathological examination revealed a lobulated myxoid dermal tumour. The tumour cells were spindle-shaped or bizarre configuration. In the lower part of the dermis the lesion contained abundant cells simulating glomus tumour or melanocytic naevus. Staining with S-100 protein, epithelial membrane antigen (EMA), neuron-specific enolase (NSE) and desmin were negative. The matrix of the tumour was positive for Alcian blue and periodic acid-Schiff (PAS). Electron microscopic examination showed that the lesion was composed of dendritic cells separated by abundant glassy matrix and varying amounts of collagen fibres. Some of the cells looked like fibroblasts, and others like perineurial cells. The histogenesis of the tumour is discussed with particular attention to histochemical, immunohistochemical, light and electron microscopic findings.