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Carcinosarcoma is a rare neoplasm that displays morphological features of both an adenocarcinoma and a sarcoma. The question is whether two tumors co-exist or whether the two morphological aspects represent sequential steps in tumor progression. We report a case of carcinosarcoma of the caecum in a young female. To characterize the two tumor cell populations and to gain insight into the pathogenesis of the lesion, we conducted immunohistochemical and ultrastructural analyses of the tumor. The biphasic aspect of the tumor showed an admixture of carcinoma and spindle-cell sarcomatoid areas. Both adenocarcinoma and sarcomatous cells were positive for cytokeratins. Vimentin was undetectable in the epithelial portion, but many of the sarcomatous cells stained for vimentin. Electron microscopic analyses of the sarcomatous portion revealed budding of "retroviral particles" from the rough endoplasmic reticulum cisternae. Our data support the contention that "carcinosarcoma" is a part of a single clinicopathological continuum with "spindle-cell carcinoma", the former being the biphasic expression of the neoplasia, the latter the monophasic expression; the presence of productive retroviral infection in the sarcomatous cells could constitute one of the additional support in tumor progression from the carcinomatous to the sarcomatous phase.

Intramuscolar mixoma is a rare benign neoplasm of mesenchymal origin consisting of stellate shaped cells in an abundant loose, mucopolysaccharide rich matrix. We report two cases of intramuscolar mixoma with review of the literature. Our objectives are to delineate the clinico pathologic characteristic, the nature of constituent cells and the features differing from others benign and malignant neoplasms.

Lipomatous tumor of palatine tonsil are rare. We report a case detected in a 72 year old male with a discussion about differential diagnosis of malignant polipoid lesions of the tonsil and some consideration about the problem of the growth of such neoformation.

Primary colonic signet ring cell carcinoma is a rare neoplasia. The prognosis is particularly poor with only very few patients surviving more than one year following diagnosis. We report a case of primary signet ring cells carcinoma of the rectum, detected in a 15 year old young male, particularly interesting for the patient young age and for good prognosis.

Thirty cases of primary hepatic carcinomas and twenty hepatic metastatic localizations with equivocal histopathological features were investigated using morphologic criteria and immunohistochemical methods. The study was performed on formalin-fixed, paraffin-embedded tissue sections from surgical removed specimens. On the basis of our experience (in according with literature data) we have shown that most of hepatocellular carcinomas express a specific morphologic pattern (i.e. contemporary cholangiocellular differentiation) and phenotypic characters (particularly CEA positivity with bile canalicular pattern). Nevertheless in some cases it is impossible to make a differential diagnosis; the evaluation of new biological parameters like proliferative index will be useful.

More than 50% of AIDS patients show adrenal compromise. The major pathological findings include inflammatory changes of both the cortical and medullary portion with necrosis and haemorrhage. The principal determinant of these abnormalities appears to be CMV infection. We also report the occurrence of focal or subtotal hypophyseal necrosis in the setting of AIDS. These alterations of endocrine glands may deserve attention in the management of the patients.