Immunoreactivity to cytokeratins in non-epithelial cells in deep gastric ulcer.

The finding of cytokeratin positivity in non-epithelial cells in 9/15 cases of performing or penetrating gastric ulcer is reported. Two different monoclonal anti-cytokeratin antibodies were used and both produced a strong positivity in spindle and polyglonal cells in the gastric wall. These cells were often distributed near the peritoneal surface, but they were also found in central parts of the gastric wall. The cytokeratin-positive cells had no connection with the gastric mucosa, lacked epithelial features in routinely stained sections and were not positively stained by antibodies to other epithelial markers (EMA and Ber-Ep 4). Many of the cytokeratin-positive cells were also positive for vimentin. There was no evidence of malignancy in any of the cases, but cytokeratin-positive cells like those in the present study may be erroneously interpreted as infiltrating carcinoma. The true nature of the cytokeratin-positive cells was not revealed in the present study. It is concluded that cytokeratin positivity must be evaluated with care and that it is valuable to add antibodies other than anti-cytokeratins for the recognition of epithelial cell differentiation.