A case of SALL4-positive adenocarcinoma in ascitic fluid cytology, suggestive of peritoneal dissemination from AFP-producing stomach cancer

Abstract

 We report a case of SALL4-positive adenocarcinoma detected by ascitic fluid cytology that suggesting peritoneal dissemination of AFP-producing stomach cancer in a man in his 60's. Large-sized, tightly packed cell clusters were observed. In addition, papillary-like protrusions were seen from the cell clusters, and sheet-like clusters were also seen. The cell clusters consisted of 1 to 2 layers, and the sheet-like clusters, in particular, were morphologically similar to mesothelial cells. Immunohistochemistry yielded negative results for all markers of mesothelial origin, while the results for some adenocarcinoma markers and SALL4 were positive. A proportion of the adenocarcinoma cells in the stomach biopsy specimens was also positive for AFP and SALL4. It was difficult to determine the primary lesion from the cell morphology, however, the SALL4 positivity provided a useful clue.