Clinicopathological analysis of a type of “low grade” poorly cohesive gastric adenocarcinoma not otherwise specified with a good prognosis

Poorly cohesive carcinoma not otherwise specified (PCGCA-NOS) is regarded in the most recent WHO classification as a high-grade malignancy; however, some cases may be associated with a relatively good prognosis. We have studied a series of 115 cases of PCGCA-NOS and were able to identify low-grade features in 14 cases based on three morphological manifestations. Immunohistochemical staining, EBER in situ hybridization, Feulgen staining and flow cytometry were employed. Among the 115 cases of PCGAC-NOS, 14 cases met the criteria of “low grade”, accounting for 12.2 %. The “low grade” cases exhibited more shallow invasion and less lymph node metastasis (both P  < 0.05); showed less frequent expression of MUC5AC, E-cadherin and p53 (all P  < 0.05). Moreover, “low grade” PCGAC-NOS had a lower proliferative index( P  < 0.001). We also found that the DNA content was lower in the “low grade” group, and aneuploidy was not detected in the “low grade” group, which was sharply different from the control group (50 %). Last, “low grade” PCGAC-NOS had a more favorable prognosis. A small subset of PCGAC-NOS cases have a low grade nature, and the clinicopathological features, immunophenotypes, and cytogenetics of these “low grade” cases differ from those of traditional PCGAC-NOS.