Primary gastric Ki-1 positive anaplastic large cell lymphoma: a report of two cases.

Two cases with primary gastric Ki-1 positive anaplastic large cell lymphoma are presented. Morphologic features of both cases involved pleomorphism of the neoplastic cells, fibrosis and lymphatic infiltration. The neoplastic cells in both cases were positive for BerH2 (CD30), LCA(CD45), lysozyme and alpha-1-antitrypsin (alpha 1-AT). In additional case, the neoplastic cells were additionally positive for MAC387 and alpha 1-antichymotrypsin (alpha 1-ACT). The neoplastic cells in these cases were negative for L26(CD20), UCHL-1(CD45RO), DAKO CD3 and epithelial membrane antigen (EMA). According to the results of the phenotypic studies, the authors consider that the neoplastic cells have some of the features of histiocytes. Both patients at 2 and 8 years after surgery without chemotherapy are disease free. This lymphoma is well known to be frequently misdiagnosed as undifferentiated carcinoma. Although rare in occurrence, recognition of this primary lymphoma in the stomach has a significant clinical implication, as the authors consider that its prognosis might be better than undifferentiated carcinoma of the stomach.