[Clear cell dermatofibroma: a case report with cytogenetic study]

We report an observation concerning a 48-year-old male who presented with a 5 cm tumour on his left leg, first noticed 18 months ago. The remainder of clinical examination was normal. Histological assessment revealed a tumoral infiltration of entire dermis and superficial hypodermis. This tumour consisted of monomorphous, ovoid or spindle cells, with clear cytoplasm and PAS+ granulations. There was strong immunoreactivity by tumoral cells only for vimentin. Ultrastructural studies revealed fibrohistiocytic-like tumoral cells, without epithelial, muscular, vascular or melanocytic differentiation. These results were consistent with the diagnosis of clear cell dermatofibroma. Cytogenetic evaluation and FISH analysis showed a deletion of p12. Clear cell dermatofibroma is a rare and recent variant of dermatofibroma, with a difficult histological evaluation and which must be differentiated from clear-cell sarcoma. This observation is the first case-report of this entity, to our knowledge, showing a cytogenetic abnormality.