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The immunohistochemically stained membrane cofactor protein of complement (MCP/CD46), one of the complement regulatory proteins, was up-regulated in some diseased kidney tissues. MCP in diseased kidneys was strongly concentrated along the glomerular capillary walls as well as in the mesangial regions, while MCP in normal kidneys was weakly detected in all glomerular structural cells and in the epithelial cells of tubules. Since the enhanced staining was noted in those areas where depositions of C3b/C3c occurred, ongoing complement reaction might be responsible for the up-regulation of MCP expression. MCP expression may be up-regulated by complement fragments generated during complement activation in glomerulonephritis. Furthermore, anti-MCP staining was stronger in intensity in patients with moderate to massive proteinuria, indicating that up-regulation of MCP expression could be directly correlated to the kidney damage.

The case is presented of a 62-year-old woman having a well-circumscribed, painless breast lump which led to the discovery of pure mammary leiomyosarcoma. There are only a few documented cases of primary leiomyosarcoma in the breast, and a brief review of the literature on the diagnostic findings and histogenesis of a smooth muscle malignant neoplasm in this site is, therefore, provided. As far as the histogenesis is concerned, ultrastructural features of the present case suggest a tumor of pluripotent mesenchymal cell nature rather than of vascular smooth muscle cell origin.

A morphologic curiosity is presented in a polypoid gastric tumor combined with adenocarcinoma and carcinoid tumor. It is likely that those two represent a composite tumor; however, the authors think it is more likely that they are two concurrent, independent collided tumors.

A 60-year-old man with pharyngeal carcinoma developed spontaneous pneumothorax. A biopsied lung tissue revealed an extensive granulomatous reaction to some yellow material. Because of the patient's frequent aspirations of the liquid diet which was mixed with an artificial lemon flavor, it is considered that the aspirated material provoked the pulmonary reaction and possibly the pneumothorax. An energy dispersive X-ray analysis of the biopsied lung tissue aided in excluding the possibility of the pulmonary reaction and the yellow material being of ubiquitous pneumoconiotic origin.