SYNOPSIS The pathological features of 12 acinar cell neoplasms of the pancreas are described; these comprise 11 carcinomas, of which seven were pure acinar cell growths and four were mixed acinar and ductal carcinomas, and one adenoma. These tumours occurred in a series of 105 during the period 1962-75. Thrombotic endocarditis developed in three out of the 11 carcinoma cases. The distinctive histological features of these neoplasms and the means of differentiating them from anaplastic carcinomas and certain other carcinomas, for example, islet cell carcinomas, oat cell carcinomas, and carcinoid tumours, are discussed. The poor prognosis of pancreatic cancers is emphasized, and reasons are put forward for believing that future epidemiological studies may need to take account of the histological types of pancreatic carcinoma.

In this study we investigated the in vitro responses of peripheral blood mononuclear preparations and purified monocytes to Clostridium difficile toxin A. In contrast to the responses of T and B cells, exposure to toxin A led to a rapid loss of monocytes in a time-and dose-dependent fashion (the majority of cells were lost within 24 h of exposure to >100 ng of toxin per ml). Transmission electron microscopy, flow cytometry, and fluorescence microscopy after propidium iodide and Hoechst staining showed that cell death in purified preparations of monocytes following exposure to 100 and 1,000 ng of toxin A per ml occurred by apoptosis. Further studies showed that 5,5,6,6-tetrachloro-1,1,3,3-tetraethylbenzimidazole-carbocyanine iodide aggregates were retained within toxin A-exposed monocyte mitochondria, but cytochrome c was released, suggesting that the apoptotic cascade was triggered in the absence of mitochondrial permeability transition. There was also an increase in caspase-3 activity in toxin A-stimulated monocytes. Following exposure to very high concentrations of toxin A (30 g/ml), monocyte cell death was predominantly of the necrotic type, with rapid extracellular release of lactate dehydrogenase. These studies demonstrated that C. difficile toxin A has a cell-specific effect, in which monocytes exhibit greater susceptibility than lymphocytes and their death is induced in a concentration-dependent manner.

The clinicopathological features of a basaloid carcinoma of the prostate gland are described in a 28-year-old man, and the management and prognosis discussed. Basaloid tumours of the prostate are very rare and only a few cases have been described in detail. Those cases which have been reported as adenoid cystic carcinoma, adenoid cystic-like carcinoma and adenoid basal cell tumour are reviewed.

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