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Background: Morphologic analysis of malignant renal tumors of childhood and adolescence has resulted in the identification of a variety of tumor types with characteristic histology and clinical behavior. The authors report a case of renal sarcoma in a 19-year-old male that differs in morphology from the various established categories of primitive renal tumors., Methods: Sections taken from the nephrectomy specimen were stained by routine methods and by immunohistochemistry for stromal and epithelial markers, and for proliferation markers. In addition, ultrastructural studies were undertaken., Results: The tumor, which the authors termed cystic embryonal sarcoma, was comprised of poorly differentiated malignant mesenchyme in a myxoid stroma. Numerous epithelial-lined cysts were present. The distribution of the cysts and proliferation kinetics of cyst-lining epithelial cells suggested that they were derived from entrapped renal tubules. The tumor showed early recurrence postoperatively and after aggressive chemotherapy. The pathologic features and clinical behavior of the tumor resemble those of 2 previously reported cases and an additional 25 cases from the files of the National Wilms' Tumor Study Pathology Center., Conclusions: The clinical and histologic features of cystic embryonal sarcoma differ from those of other renal tumors of childhood and adolescence, and the tumor appears to be a novel form of renal malignancy.

Identification of contaminating tissue fragments as "floaters" is a common problem in surgical pathology. They may be introduced at several steps in the processing of specimens, and they are capable of causing interpretative consternation. Using immunohistochemistry with monoclonal antibodies to blood group isoantigens A, B, and H, we studied nine cases in which floaters were present. In five of the study cases, discordant blood group immunostains allowed identification of the artifactual tissue fragments. By chance, the other four specimens contained probable floaters from patients whose blood groups were concordant with those from whom the "native" tissue had been obtained. These results indicate that in some instances, blood group immunostains may resolve interpretative difficulties surrounding floaters. It is likely that application of immunostains, directed at additional blood group antigens, will extend the utility of this procedure.

Background: The aim of this study was to combine an epidemiologic survey of colorectal cancer among Maori, Polynesian, and white inhabitants of New Zealand with a detailed analysis of tumor subsite and histopathology., Methods: Data were obtained from the New Zealand National Cancer Registry and included all registrants from 1970 to 1984. Sections of histologic specimens of colorectal cancer of Maori and non-Maori were retrieved from three Auckland hospitals., Results: The annual age-adjusted incidence rates of large intestinal cancer among male and female Maoris and male and female Polynesians were 40%, 40%, 39%, and 29%, respectively, of the total population incidence. Time-trend analysis showed the incidence of large intestinal cancer to be increasing among all racial groups. The relative proportion of rectal cancers was higher in male and female Maoris and female Polynesians than in the general population, whereas male Polynesians had a relatively high proportion of right colonic cancers. High-grade carcinoma and mucinous carcinoma occurred more frequently in young individuals regardless of race. Carcinomas were diagnosed at a more advanced stage in Maoris., Conclusion: Given the similar environmental characteristics of the three racial groups, the findings indicate the presence of powerful protective factors in Maoris and Polynesians. These could be constitutional or mediated by unrecognized dietary constituents.

The development of stapling instruments has obviated the need to perform anal mucosectomy for ulcerative colitis, but the potential exists for continued inflammation and, perhaps, malignant change. We reviewed the pathology specimens of patients who had had restorative proctocolectomy, to determine the incidence and severity of inflammation in the anal mucosa.