Yoshimasa Ishii

Malignant rhabdoid tumor of the colon: report of a case.

A malignant rhabdoid tumor of the colon is very rare and only three cases have been previously described. A 76-year-old man was admitted to the hospital complaining of epigastralgia. An elastic mass was palpable in the right upper abdomen. A barium enema and endoscopic examination showed a giant gyrate tumor arising from the cecum. Abdominal ultrasonography and a computed tomography scan revealed the tumor to be located in the colon associated with multiple liver metastases and gallbladder stones. A right colectomy and cholecystectomy were thus performed. The tumor was histologically composed of sheets of large round and polygonal nuclei with vesicular chromatin, and abundant acidophilic cytoplasm, often containing hyalin-like inclusion. The cytoplasm was positive for vimentin and neuron-specific enolase, and hyaline globules of the rhabdoid tumor cells stained positive for cytokeratin in some cells. Transmission electron microscopy showed characteristic rhabdoid cells with an aggregation of intermediate filaments. A histologic diagnosis of malignant rhabdoid tumor of the colon was made. The tumor demonstrated several unusual findings for malignant rhabdoid tumors including diploidy by a flow cytometric analysis, and positive nuclear immunohistochemical staining for p53 protein and Ki-67 antigen. We report herein the third known case of a pure colonic rhabdoid tumor.

Ectopic expression of MECA‐79 as a novel prognostic indicator in gastric cancer

The aim of this study was to clarify the clinical implications of a unique carbohydrate determinant, MECA‐79, in gastric cancer specimens and cells. Immunohistochemical analysis showed that 62 of 225 (27.6%) cases were defined as positive for MECA‐79. MECA‐79 expression was correlated with depth of invasion, venous invasion, TNM stage, and distant metastasis. In survival analyses, patients with MECA‐79 expression had worse prognosis by the log–rank test. Multivariate analysis of the Cox proportional hazard model showed that MECA‐79 expression was an independent factor of a worse cancer‐specific survival. Among 11 gastric cancer cells, MECA‐79 was observed in only MKN7 cells, which also expressed GlcNAc6ST‐2 transcript. A knockdown of GlcNAc6ST‐2 in MKN7 cells showed a markedly reduced expression of MECA‐79, suggesting that GlcNAc‐sulfation of MECA‐79 is mainly synthesized by GlcNAc6ST‐2. Furthermore, real‐time RT‐PCR analysis revealed that GlcNAc6ST‐2 was significantly increased in cancer tissues compared with paired normal mucosa. In conclusion, the expression of MECA‐79 could be a useful marker for the prognosis of gastric cancer. Our results might also provide novel perspectives on the biology of MECA‐79 and GlcNAc6ST‐2 in cancer progression and metastasis. (Cancer Sci 2011; 102: 1088–1094)