Histopathological study using computer database of 10 000 consecutive gastric specimens: (2) malignant lesions.

Using a computer database, the author investigated the histopathology of 10 000 consecutive gastric specimens collected in the last 12 years 2002-2013 at his pathology laboratory in a relatively large hospital in Japan. Examination of histological sections was done when appropriate. The gastric specimens were made up of 8579 benign conditions and 1421 malignant lesions. The latter comprised gastric carcinoma in 1342 cases (94.4%), gastrointestinal stromal tumor (GIST) in 34 (2.4%), mucosal-associated lymphoid tissue (MALT) lymphoma in 25 (1.8%), non-Hodgkin's malignant lymphoma in 19 (1.3%), and metastatic carcinoma in 1 case (0.1%). Of the 1342 cases of gastric carcinoma, the histological type was as follows: tubular adenocarcinoma in 755 cases, papillary adenocarcinoma in 176, mucinous adenocarcinoma in 147, signet ring cell carcinoma in 145, poorly differentiated adenocarcinoma in 114, adenosquamous carcinoma in 4, and metastatic small cell carcinoma from the lung in 1. In surgically resected cases, the number of early gastric carcinomas was 258 and of advanced carcinoma, 521 cases. In GIST (n = 34), there were 2 cases of the epithelioid type and 32 of the spindle cell type. The size of GIST ranged from 1-15 cm, with a mean of 5.6 cm. KIT (CD117) was positive in 34/34 cases, CD34 in 31/34, desmin 2/34, and S100 4/34. A genetic analysis was performed in 6 cases of GIST, all of which showed point mutation of KIT and/or PDGFRA genes. In MALT lymphoma (n = 25), centrocyte-like cells and lymphoepithelial lesions were seen in every case. Helicobactor pylori infection was noted in 92%. In non-Hodgkin's lymphoma (n = 19), 17 cases were of diffuse large B-cell lymphoma, and 1 was peripheral T-cell lymphoma, while 1 was NK-cell lymphoma.