Neuron-specific enolase is a marker of cutaneous Langerhans' cell histiocytosis ("X")-a comparative study with S100 protein.

The immunohistochemical expression of neuron-specific enolase (gamma/gamma) (NSE) was studied comparatively with S100 protein in a group of Langerhans-cell-type ("X") (n = 8) and non-Langerhans-cell-type ("non X") (n = 24) cutaneous histiocytoses. NSE was expressed by the majority (70-90%) of histiocytic cells in all cases of Langerhans-cell histiocytoses, whereas it was absent from non-Langerhans-cell histiocytoses. S100 protein was expressed by the majority of Langerhans-cell histiocytosis cells but also by a small percentage (1-5%) of cells in non Langerhans-cell histiocytoses. These results show that NSE is almost as sensitive as, but more specific than, S100 protein in discriminating Langerhans-cell from non-Langerhans cell cutaneous histiocytoses, and that it consequently represents a useful adjunct in the immunohistochemical diagnosis of histiocytic skin diseases.