Intranuclear and intranucleolar tubular inclusions in gastric adenocarcinoma cells.

A case of poorly differentiated intestinal-type gastric adenocarcinoma with ultrastructural evidence of a neuroendocrine differentiation, including rare neurosecretory granules and microtubules, is reported. Tumor cells often showed irregularities of the nuclear contour ranging from invaginations to nuclear projections and pockets. Intranuclear and intranucleolar tubular inclusions were observed, and their morphogenetic relation with the nuclear envelope is discussed. This appears to be the first report describing intranucleolar tubular inclusions in a human tumor.