Collecting duct carcinoma of the kidney: a report of three cases and review of the literature.

Collecting duct carcinoma (CDC) of the kidney is a rare neoplasm arising from the medullary collecting ducts. The clinicopathological features of three cases are here presented to add to the 42 cases reported so far in the English language literature. Hematuria is the most common presenting symptom, although 10% of patients present with metastatic disease, often in neck lymph nodes. The tumor mass is typically centred on the medulla of the kidney and extends into the cortex. Radiological diagnosis may be difficult because the radiological features of CDC are poorly described. The histological appearances have been described as tubulo-papillary, tubular, solid and sarcomatoid. Intracytoplasmic mucin may be present. The typical immunohistochemical profile is positive staining with antibodies for low and high molecular weight keratin and epithelial membrane antigen (EMA) and positive staining with the lectin Ulex europaeus agglutinin. Literature reports of cytogenetic characterisation show loss of chromosomes resulting in monosomies. Prognosis is poor as more than half of the reported cases have developed metastases or died within two years of presentation.

Fat necrosis in surveillance biopsies of heart transplants.

Fat necrosis was observed in surveillance biopsies of five patients following heart transplant. This reaction is poorly documented in the literature, but in personal communication, some pathologists working in the field have had experience with it. Four of the cases developed two to six days after transplantation, but in the fifth case, fat necrosis developed ten months after transplantation. Autopsy study of one case showed extensive severe fat necrosis involving both donor and recipient tissues. The cause is not known, and the changes are independent of rejection. However, the fat necrosis can be found within the interstitial tissues of the myocardium and subendocardium and may be mistaken for rejection if lymphocytes and polymorphs are part of the inflammatory response. The only clinical finding thought to be related to the fat necrosis was the development of transient complete heart block in a patient in whom the International Society for Heart and Lung Transplantation (ISHLT) standardised rejection grading was never greater than IA.

The role of the thymus in the maintenance of natural killer cells in vivo.

This report describes a model for investigating the role of the thymus in regulating natural killer (NK) cell activity in vivo. Evidence is presented that the thymus can regulate NK cells, and that at least some NK cells can develop without thymic help. Marrow from thymectomized rats depleted of circulating T cells by thoracic duct cannulation was transplanted into rats without a thymus (1 degree ATX.BM). These 1 degree ATX.BM rats had NK cell levels above controls 3 months after reconstitution but markedly depressed NK cell levels by 9 months. When 1 degree ATX.BM marrow was used to reconstitute rats with or without a thymus, those without a thymus (2 degrees ATX.BM) exhibited low NK cell levels after 3 months, and a similar result was obtained when 2 degrees ATX.BM marrow was used to reconstitute 3 degrees ATX.BM rats. The low NK cell levels in 2 degrees and 3 degrees ATX.BM rats were due to a deficiency in spontaneously cytotoxic NK cells, as they had normal numbers of interferon-responsive pre-NK cells. Spleen cells from 2 degrees and 3 degrees ATX.BM rats produced less interferon than control spleen cells when cultured with P815 tumor cells in vitro. However, 2 degrees and 3 degrees ATX.BM rats had higher numbers of large granular lymphocytes than controls despite their low NK cell levels. In marked contrast to 2 degrees and 3 degrees ATX.BM rats, spleen cells from 4 degrees ATX.BM rats had higher levels of cytotoxicity and a higher frequency of both spontaneously cytotoxic and pre-NK cells than controls. The 4 degrees ATX.BM rats also had the highest frequency of large granular lymphocytes in the spleen.