Immunohistochemical analysis of invasive micropapillary carcinoma pattern in four cases of gastric cancer.

Gastric cancer with the invasive micropapillary carcinoma (IMPC) pattern has been reported to be a variant with poor prognosis and rapid progression. To the best of our knowledge, only 4 cases of gastric cancer from Japan and 11 cases from Korea have been reported to contain the IMPC pattern. In the present study, 4 cases of gastric cancer containing the IMPC pattern from 2 Japanese men and 2 Japanese women are reported. The cancer tissues, including a recurrent lesion in 1 case and lymph node metastases in 2 other cases, were examined immunohistochemically to identify suitable markers for demonstrating the peculiar "inside out" pattern of IMPC and for analyzing HER2 expression. A characteristic IMPC pattern occupied more than 10% of each cancer tissue in these 4 cases. Lymphatic invasions were very often detected; in fact, lymph node metastases were detected in 3 out of 4 cases. The unique "inside out" pattern in IMPC was clearly revealed in all cases by staining with antibodies to both epithelial membrane antigen (EMA) and KL-6, but not with an antibody to CD10. HER2 was positive in 3 of 4 cases with the IMPC pattern, including cases with a recurrent lesion or lymph node metastases. Fluorescence in situ hybridization (FISH) analyses disclosed positive results in case 1, and case 3 including lymph node metastatic foci. Highest FISH titer was 6.8 in case 1, revealing marked amplification of HER-2 gene. Four cases of gastric cancer with the IMPC pattern were reported. EMA and KL-6, but not CD10, were particularly useful markers for visualizing the characteristic "inside out" pattern of the IMPC pattern in stomach cancers, similar to the markers for breast and urinary bladder cancers.

[Mucoepidermoid carcinoma of the intrahepatic bile duct with metastasis to the cranial skin].

Mucoepidermoid carcinoma of the intrahepatic bile duct is a rare variant of cholangiocarcinoma: it is composed of mucus-secreting squamous cells and glandular cells within the same nests. This tumor is very aggressive, with high-grade malignancy, and has a poor prognosis. In the international literature, only 17 cases of mucoepidermoid carcinoma originating in the hepatic bile duct system have been reported until now. We report an autopsy case of mucoepidermoid carcinoma of the intrahepatic bile duct with metastasis to the cranial skin in a Japanese man who was more than 70 years old. This cancer metastasizes to many organs, but skin metastasis is extremely rare.

Immunohistochemical and electron microscopic studies of a case of duodenal gangliocytic paraganglioma.

Gangliocytic paraganglioma (GPG) is a rare tumor, occurring almost exclusively in the duodenum. In the present case, a submucosal tumor 2.5 x 2 x 1.5 cm in size was located on the anal side of the papilla of Vater, with clear margins and without capsule on cut-surface examination. Tumor cells included three types of cells: ganglion-like cells (GCs), endocrine cells (ECs), and Schwann cells (SCs). The GCs were large with eccentric nuclei with large nucleoli and clear abundant cytoplasm. ECs were detected in small nests, surrounded by bundles of SCs. Immunohistochemically, GCs were positive for synaptophysin, neuron-specific enolase (NSE), and CD56. ECs were positive for chromogranin A, NSE, somatostatin, pancreatic polypeptide, and CD56, and were associated with S100 protein-positive SCs. On fine structural examination, ECs contained numerous membrane-bounded secretory granules, 250-450 nm in diameter, in their cytoplasm, surrounded by a branched, complex basal lamina. SCs possessed basal lamina along their long interlacing cytoplasmic processes. The histogenesis of GPG most likely involves proliferation and differentiation of pluripotent stem cells in the duodenal crypts in the duodenum as a true tumor, although it is also possible that the retroperitoneal components of both GCs and SCs proliferate, together with ECs, from ventral primordial tissue of the pancreas in the duodenum. The immunohistochemical and ultrastructural findings of a case of GPG are reported, focusing on three major cellular components: GCs, ECs, and SCs.