Renin producing neuroendocrine pancreatic carcinoma--a case report and review of the literature.

A 44 year old male patient presented with severe hypertension. The diagnostic work-up revealed elevated levels of plasma renin activity (about 10 times the upper limit of normal) in the presence of normal plasma aldosterone levels and serum potassium concentrations. Renovascular disease was excluded by angiography. Selective renal vein sampling did not show any renin gradient. CT-scans of the abdomen demonstrated normal morphology of the kidneys and adrenals but revealed a big mass in the pancreatic corpus and tail with infiltration of the splenic vein and the presence of enlarged local lymph nodes. The endocrine nature of the pancreatic mass was further supported by a positive octreotide scintigraphy scan. Surgical removal of the tumor by left sided pancreatectomy combined with splenectomy resulted in rapid normalization of elevated renin concentrations as well as blood pressure. Histological examination of the tumor tissue revealed the presence of a neuroendocrine pancreatic carcinoma. Highly (x 70) elevated renin levels were detected by radioimmunoassay in the tumor tissue. To our knowledge this is the first renin-producing neuroendocrine pancreatic carcinoma described in the literature. The present paper describes the case in detail and reviews the available literature on clinical symptomatology, diagnosis and treatment of renin-producing tumors.

Alpha-fetoprotein-producing gastric cancer mimicking extragonadal testicular cancer.

A case of alpha-fetoprotein-producing gastric hepatoid adenocarcinoma mimicking an extragonadal testicular cancer in a 28-year-old man is presented. This rare kind of tumor should be included in differential diagnosis in young patients without evidence of primary testicular malignancies.

Desmosomal plakophilin 2 as a differentiation marker in normal and malignant tissues.

Plakophilin 2 (PKP2) is a widespread protein which shows a remarkable dual location: On the one hand, it appears as a constitutive karyoplasmic protein and on the other it is a desmosomal plaque component of most, probably all, desmosome-possessing tissues and cell culture lines. Here we report on its desmosomal occurrence as revealed by immunocytochemical results obtained with three PKP2-specific murine monoclonal antibodies (mAbs) PP2-62, PP2-86 and PP2-150. These mAbs detect PKP2 in characteristic desmosomes of most normal cells, including simple and stratified epithelia as well as non-epithelial tissues such as myocardium and lymph node follicles. In addition, however, several normal tissues consistently display a differentiation-related PKP2 distribution, for example an absence of immunostaining in the "keratinizing" local specializations of the thymic epithelial reticulum, i.e. Hassall's corpuscles, and the restriction of PKP2 to the stratum basale of most stratified squamous epithelia, in contrast to its absence in upper strata, which contain PKP1- or PKP3-rich desmosomes instead. Taking advantage of the reactivity of mAb PP2-150 with formalin-fixed, paraffin-embedded material, a series of human carcinomas (n = 37) has also been analyzed. The results suggest that mAbs to PKP2 may serve as markers for the identification and characterization of carcinomas derived from--or corresponding to--simple or complex epithelia. Thus consistent PKP2 immunostaining has been observed in all 18 cases of adenocarcinomas tested, but more variable and heterogeneous staining has been noted in squamous cell carcinomas, depending on the specific tumor type. The potential value of such mAbs for cell typing in normal and embryonic tissues and for detecting cell subpopulations with different degrees of differentiation is discussed with respect to their possible application in tumor diagnosis.

Adipophilin is a specific marker of lipid accumulation in diverse cell types and diseases.

We report the human DNA and protein sequence of adipophilin and its association with the surface of lipid droplets. The amino acid sequence of human adipophilin has been determined by using cDNA clones from several tissues and confirmed by the reverse transcription/polymerase chain reaction method and Edman sequencing. The open reading frame of adipophilin encodes a polypeptide with a calculated molecular weight of 48.1 kDa and an isoelectric point of 6.72. By immunofluorescence and electron-microscopic localization with newly raised specific poly- and monoclonal antibodies, we show that this protein is not restricted to adipocytes as previously indicated by studies of the mouse homologous protein, adipose-differentiation-related protein. Adipophilin occurs in a wide range of cultured cell lines, including fibroblasts and endothelial and epithelial cells. In tissues, however, expression of adipophilin is restricted to certain cell types, such as lactating mammary epithelial cells, adrenal cortex cells, Sertoli and Leydig cells of the male reproductive system, and steatosis or fatty change hepatocytes in alcoholic liver cirrhosis. Our results reveal adipophilin as a possible new marker for the identification of specialized differentiated cells containing lipid droplets and for diseases associated with fat-accumulating cells.