Primary invasive micropapillary carcinoma of the stomach.

Reported herein is the case of a 74-year-old man with an unusual gastric carcinoma that developed at the lesser curvature of the stomach. The tumor consisted of small clusters of carcinoma cells surrounded by clear spaces, with histopathology similar to invasive micropapillary carcinoma (IMPC) of the breast. The carcinoma cells, which had downregulation of E-cadherin expression, invaded the subserous tissue and metastasized to the perigastric lymph nodes. IMPC, an unusual subtype of invasive breast carcinoma, is known to have frequent lymph node metastases, resulting in a poor clinical outcome. Although IMPC has been reported in breast, urinary bladder, ureter, lung, salivary gland and colon, to the best of the authors' knowledge this is the first report of IMPC arising in the stomach. Presented here are the clinicopathological features of primary IMPC of the stomach.