Relationship between skeinoid fibers and stromal matrix in gastrointestinal stromal tumors: morphometric analysis with quick-freezing and deep-etching method.

Our previous study of a gastrointestinal autonomic nerve tumor with skeinoid fibers (SF) using the quick-freezing and deep-etching method, suggested that the distance between one radix and a neighboring radix (DRNR) in pre-existing meshwork structures around the tumor cells is consistent with the periodicity of the SF. Therefore, measurement of the DRNR in the meshwork could clarify the significance of the pericellular matrix for SF development. In the present study, we analyzed the meshwork in three cases of gastrointestinal stromal tumor (GIST), which showed different immunohistochemical stainings, but confirmed to have smooth muscle differentiation (SMD) by immunohistochemistry and/or electron microscopy. The DRNR from the three cases of GIST showed similar histogram patterns (a peak of 20-30 nm, mean values of 28.02, 25.74 and 26.45 nm), which were significantly shorter than the periodicity of SF (a peak of 40-45 nm, mean value of 42.14). Although we need further studies with additional GIST cases, we speculate that the pericellular matrix of GIST with SMD is not suitable for SF development.

Heterotopic pancreatic tissue associated with intra- and extrahepatic choledochal cysts.

A case report of heterotopic pancreas in intra- and extrahepatic biliary tracts in a 36-year-old female who suffered from intra- and extrahepatic choledochal cysts with an anomalous pancreatobiliary duct system. Histologic examination of the resected specimen showed pancreatic tissues located along the wall of the biliary tract with choledochal cysts. The pancreatic tissue consisted of acinar cells and duct elements without Langerhans' islets; the acinar cells were positive immunohistochemically for alpha-amylase and negative for endocrine hormones. Ultrastructural study revealed zymogen granules in the acinar cells. In the present case the heterotopic exocrine pancreatic tissue seems to be etiologically related to choledochal cysts as well as to the anomalous arrangement of the pancreatobiliary duct.

Immunohistochemical localization of ganglioside components in hepatocellular carcinoma and liver cirrhosis using monoclonal antibody.

BACKGROUND: In our previous studies (1, 2) a remarkable difference in the patterns of gangliosides was demonstrated between normal human liver and hepatocellular carcinoma (HCC) on thin layer chromatography, consisting of a marked increased in GM2 and the unidentified gangliosides. The proliferation of the unidentified gangliosides was also revealed in certain types of liver cirrhosis. The precise chemical structure of the unidentified components still remains to be elucidated, and there are no comprehensive data on these components investigated in liver tissue from patients with liver cirrhosis, HCC, or malignancies of the biliary and gastrointestinal tracts. In view of this, we studied the immunohistochemical localization of these ganglioside components in these tissues. EXPERIMENTAL DESIGN: Two unidentified gangliosides were extracted and monoclonal antibody were prepared. Localization of these gangliosides on tissue sections of liver obtained from HCC and liver cirrhosis, and malignancies of the biliary and gastrointestinal tracts was investigated by performing immunohistochemical staining using monoclonal antibody. The carbohydrate composition and sialic acid species of these components were determined by gas-liquid chromatography analysis. The sialic acid linkage to the terminal moiety of these components was also investigated by sialidase treatment. RESULTS: Staining with monoclonal antibody against specific gangliosides revealed dense brown granules in HCC tissue sections, whereas normal liver, kidney, and spleen sections were negative. Tissue sections of cirrhotic livers generally stained weakly except one case that showed slight to moderate staining. These antigens were immunohistochemically negligible in sections from one case each of gastric, colon, and common bile duct cancer. The ganglioside components identified in HCC were confirmed to be sialosylparagloboside with an alpha 2-6galactosyl terminus as determined by gas-liquid chromatography analysis and enzymatic hydrolysis with different sialidases. CONCLUSIONS: These components may be a useful marker in the detection of HCC and for subclassification of HCC from the standpoint of ganglioside metabolism.

Neurothekeoma. Report of a case with immunohistochemical and ultrastructural studies.

A case of neurothekeoma in a 52-year-old woman is reported. The tumor developed on the medial aspect of the right nostril as a well-demarcated, dome-shaped, erythematous nodule of rubbery consistency. Microscopically, it consisted of numerous nests and cords of spindle-shaped cells in the dermis. Some of the tumor cell nests appeared epithelial-like, while the other areas showed a myxomatous appearence with various amount of mucinous matrix in the intercellular space. Neurothekeoma is a benign cutaneous tumor, and is considered to be of schwann cell origin. In the present case, the tumor cells did not stain positively for S-100 protein, despite the light microscopic suggestion of peripheral nerve origin. Ultrastructurally, most tumor cells contained a large number of myelinoid figures. This ultrastructural finding appears to be a useful diagnostic characteristics of neurothekeomas.