A series of 12 cases of pancreatic carcinoma with sacroma-like transformation were studied. Four distinctive histologic types were identified: spindle cell carcinoma, malignant giant cell tumor, pleomorphic giant cell carcinoma, and round cell anaplastic carcinoma. The spindle cell carcinoma had a predominance of malignant spindle and undifferentiated cells. Hemorrhage and sarcomatoid stroma with abundant osteoclast-like giant cells were the features in the malignant giant cell tumor. The pleomorphic giant cell carcinoma was characterized by abundant malignant giant cells. The round cell anaplastic type was formed by monotonous sheaths of small, round, and plump cells with rare giant cells. The first three types are considered to be ductal in origin, whereas the fourth type is believed to arise from acinar or possibly insular tissue. The differential diagnosis includes various types of true sarcoma. Although the malignant giant cell tumor of the pancreas might have a better prognosis, the prognosis in the other three types does not differ significantly from that of the ordinary type of pancreatic carcinoma.

Solitary fibrous tumours are uncommon spindle cell neoplasms generally associated with serosal surfaces, especially the pleura (‘localized fibrous mesothelioma’). Recently, these tumours have been documented in extraserosal sites. We report two solitary fibrous tumours, including one occurring in the paediatric age group, arising in two previously unreported locations, parapharyngeal space and epiglottis. These cases expand the range of sites where this tumour may originate and confirm the tendency of extrapleural cases to involve the upper respiratory tract and adjacent structures.

We report two cases of an unusual type of subpubic cystic mass occurring in postmenopausal women. They are formed by fibrocartilaginous tissue with extensive cystic degenerative changes and appear to be related to and perhaps originating from the periarticular tissues of the symphysis pubis. We could not find any reference to this lesion either in the standard gynecology and pathology textbooks or in a search of the published literature.

Ultrastructural study of five typical lesions of dermatofibrosarcoma protuberans revealed that the basic cell is fusiform and has a somewhat indented nucleus and an even distribution of cytoplasmic organelles. Fragments of basal lamina, intercellular junctions, abundant intercellular fibers, and a tendency to form cellular sheaths also were found. The tumor cells had a strong resemblance to pericytes and perineural cells, as well as marked ultrastructural similarities to neurofibroma. The authors conclude that dermatofibrosarcoma protuberans arises from a primitive fibroblastic cell with a "sheath forming cell" differentiation that has a closer relationship to the perineural cell than to the pericyte.

Four cases of malignant giant cell tumor of soft parts (MGCT) were studied ultrastructurally. Most of the cells in three cases were identified as undifferentiated mesenchymal cells and mononuclear monohistiocytic cells. The osteoclastlike cells seemed to arise from fusion of monohistiocytic cells. Immature fibroblastic cells, occasionally containing filaments with densities, were also present. They were scarce in three cases and predominant in the fourth. It was concluded that MGCT is a mesenchymal sarcoma with a bimorphic--monohistiocytic and fibroblastic--differentiation. MGCT is therefore considered a special variant of malignant fibrous histiocytoma.