Gastric carcinoma with shadow cell differentiation in metastatic lymph nodes

A case of gastric carcinoma showing shadow cell differentiation (SCD) in metastatic regional lymph nodes was presented. The tumor histologically revealed features of poorly differentiated adenocarcinoma with focal squamoid components. The metastatic lymph node lesion exhibited similar histological features and was partially intermingled with shadow cell nests (SCNs) that were reminiscent of those seen in cutaneous pilomatricoma (PMX). Immunohistochemically, tumor cells around SCNs exhibited nuclear accumulation of beta-catenin and similar staining patterns for apoptosis-related molecules as those observed in PMX. This is the first report of gastric carcinoma with SCD and re-confirmed the common characteristics of carcinoma with SCD, such as modes of cell death and nuclear accumulation of beta-catenin.