Lymphoepithelioma-like carcinoma of the skin with spindle cell differentiation.

Background: Primary cutaneous LELC is a cutaneous neoplasm with histopathologic features identical to those seen in the undifferentiated subtype of nasopharyngeal carcinoma. It is extremely rare, with only approximately 30 cases reported in the literature.

Methods: We report a case of primary cutaneous LELC arising on the forehead of a 72 year-old male in which a proportion of the neoplastic cells demonstrated distinctive spindle cell morphology.

Results: Microscopic examination showed a dense lymphoplasmacytic infiltrate admixed with large spindle-shaped cells with vesicular nuclei, prominent nucleoli, and frequent mitotic figures. These cells were negative for an extensive panel of immunohistochemical markers and positive only for broad-spectrum cytokeratins and epithelial membrane antigen. There was no connection between the tumor and the epidermis and no epidermal dysplasia. In situ hybridization for Epstein-Barr virus was negative.

Conclusions: The spindle cell differentiation in this case is unusual and suggests that in some cases the differential diagnosis of cutaneous spindle cell neoplasms might include primary cutaneous LELC.