Gastric adenocarcinoma with rhabdoid morphology.

Extrarenal rhabdoid tumors (ERRTs) are very rare neoplasms and have been reported in a range of organs, including sixteen cases in the stomach. We describe a woman aged 86 years who had an advanced gastric tumor with lymph node metastasis. The tumor mostly showed a diffuse arrangement with a small glandular region. The tumor cells were non-cohesive and had polygonal morphology with eccentric vesicular nuclei, prominent nucleoli, and abundant eosinophilic cytoplasm, i.e. they showed rhabdoid features. Immunohistochemically, the rhabdoid tumor cells were strongly positive for cytokeratins and vimentin. However, a candidate tumor suppressor gene of rhabdoid tumors, the INI1 gene, showed no mutations or loss of expression in the tumor cells. Although ERRTs typically have an aggressive clinical course, the patient was still alive without any evidence of recurrence or metastasis at 26 months after surgery. The rhabdoid features of the present case seemed to be a variant of gastric adenocarcinoma.