For just over 100 years, adamantinoma has been recognized as a primary bone tumor with epithelial characteristics and predominantly involving the tibia. Osteofibrous dysplasia is a fibro-osseous lesion also predominantly confined to the tibia with radiologic features similar to those of adamantinoma. This lesion has been shown by immunohistochemical studies to frequently contain cytokeratin-positive epithelial cells. More recently, a third group of cases with clinical and radiologic features similar to those of osteofibrous dysplasia have demonstrated more overt strands of epithelial cells within a fibro-osseous background and have been categorized as "differentiated", "regressive", "juvenile intracortical" or "osteofibrous dysplasia-like" adamantinoma. Cytokeratin subset immunohistochemical stains and cytogenetic studies performed in recent years suggest a common histogenesis for these three entities. This article reviews the clinical, radiologic and pathologic features of these entities as well as their prognostic significance. It also reviews the results of the immunohistochemical and cytogenetic studies which establish a common histogenetic relationship.

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Epidermal cyst within a toe phalanx is an extremely rare condition. It is important to differentiate this benign lesion, which can be easily treated by curettage, from other benign and malignant lesions of the bone with a similar clinical presentation, and which may require amputation of the toe. This report describes one such lesion in the mid-phalanx of the fourth toe in a 48-year-old woman, and which was successfully identified by intra-operative frozen diagnosis and treated by curettage.

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An ultrastructural study of three cases of hemangiopericytoma showed cells partially or completely enveloped by well-formed basement membrane and basement membrane-like material. The cells exhibited prominent cytoplasmic filaments, some showing dense body formation, interdigitating cytoplasmic processes, and pinocytotic vesicles. A review of the literature revealed only 19 other cases of hemangiopericytoma studied by electron microscopy, and these included seven cases of meningeal origin ("angioblastic meningioma"). The most consistent feature seen in all but two cases was the presence of a basal lamina or basal lamina-like material either partially or completely surrounding tumor cells and separating endothelial cells from pericytes. The light microscopic diagnosis of hemangiopericytoma is difficult, and there is a tendency to append the diagnosis to a variety of other tumors with a prominent vascular pattern in which other specific diagnoses are not immediately evident. The presence, ultrastructurally, of well-developed basement membrane, myogenic type filaments, and pinocytotic vesicles in a tumor with light microscopic features suggestive of hemangiopericytoma would consolidate the diagnosis and usually eliminate diagnostic uncertainty.

A Clinicopathologic study of 51 patients with endoscopically removed large bowel polyps showing histologic evidence of malignancy, either focally, to a massive extent, or comprising the entire polyp, revealed only one absolute finding capable of predicting residual disease, namely, the presence of cancer at the resection line. Of 23 radical resections, only one was justified. This case showed evidence of residual disease in the colectomy specimen that could have been predicted on the basis of involvement of the diathermy margin by carcinoma. Of 28 patients having polypectomy alone, 1 patient developed a Dukes' B carcinoma. The polyp, removed 9 months previously from the same site, had shown involvement of the margin by carcinoma. A conservative approach is thus advocated in the absence of this finding.

An osteogenic sarcoma occurring in a 22‐year‐old woman was found to be associated with production of a large amount of beta human chorionic gonadotrophin (B‐hCG). Pregnancy was excluded on the basis of a normal ultrasonogram and a proliferative type endometrium obtained by curettage. A homogenate of the tumor was strongly positive for B‐hCG while immunohistochemical staining of the tumor cells was strongly positive for B‐hCG and negative for pregnancy associated glycoprotein. These results indicate ectopic production of hCG by the osteosarcoma.

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