S100 PROTEIN-POSITIVE HUMAN BREAST CARCINOMAS - AN IMMUNOHISTOCHEMICAL STUDY

An immunohistochemical study for S100 protein was performed on 95 huma n breast carcinomas. S100 protein positive carcinoma cells were recogn ized in 54 cases (57%). The S100 protein positive and negative carcino mas were then compared in terms of stage, histologic type, nuclear gra de, appearance of minute calcification, immunoreactivity for estrogen receptor (ER), tumor recurrent pattern, and prognosis. The S100 protei n positive cases had a tendency to show a low nuclear grade (P < 0.01) . They were also more often seen in the ER positive group. For further analysis of the nature of S100 protein positive carcinoma cells, immu noreactivity for neuron-specific enolase (NSE) and actin was investiga ted. The positive staining for NSE and actin was seen in 46 cases (48% ) and 3 cases (3%), respectively. There was, however, no specific corr elation among the S100 protein, NSE, or actin staining. The nature of S100 protein positive carcinoma cells still remains unclear. The S100 protein positive carcinomas, however, exhibit relatively better charac teristics. (C) 1994 Wiley-Liss, Inc.