[Diffuse large B-cell lymphoma initially manifested by massive ascites and a small gastric lesion, clinically mimicking primary effusion lymphoma (PEL) in the abdominal cavity: a case report and review of the literature on Japanese PEL patients].

A 50-year-old man was admitted because of increasing massive ascites. While lymphoma cells (diffuse large B-cell lymphoma: DLBCL) were detected in the ascites, pleural effusion, cerebrospinal fluid and bone marrow, no tumor masses other than a submucosal lymphoma lesion in the stomach only 1 cm in diameter were identified. The patient was treated with chemotherapy including rituximab (R-CHOP-ESHAP) and injection of methotrexate and dexamethasone into the medullary cavity as well as radiation to the whole brain, and achieved complete remission 4 months later. The present case suggests that DLBCL can initially manifest as a form of effusion lymphoma with minimum solid tumor component. The distinctive clinical features of Japanese patients with primary effusion lymphoma are also reviewed.

Metastatic colon cancer mimicking Crohn's disease.

A 66-year-old Japanese woman presented with intestinal obstruction and right-sided hydronephrosis. Although upper gastrointestinal endoscopy demonstrated signet-ring cell gastric carcinoma, colonoscopy and barium enema study yielded findings mimicking Crohn's disease in the colon, that is, skipping longitudinal ulcer scarlike strictures, cobblestone appearance, segmental stricture, and pseudosacculations. After total gastrectomy and right-sided hemicolectomy, the final diagnosis of gastric cancer extensively involving the colon, and not of Crohn's disease complicating gastric cancer, was established. Pathologic examination showed that anaplastic cancer with exuberant desmoplastic reaction and infiltration along the mesenteric border principally accounted for the morphological similarities noted between Crohn's disease and metastatic colon cancer in this case. The findings in the present case, together with a review of the literature, suggest that metastatic colon cancer should be considered when Crohn-like colonic findings are encountered, not only in individuals with concurrent cancer in other sites but also in those with distant history of cancer.