Cardiovascular lesion of carcinoid syndrome. An autopsy case of bronchial carcinoid.

An autopsy case of a 67-year-old Japanese male is presented. He had been suffering from carcinoid syndrome for 5 years and showed a typical picture of carcinoid heart disease. In Japan, carcinoid heart disease is rare and we can find only four reported cases (33% of reported carcinoid syndrome). The patient had high urinary secretion of 5-HIAA and high serum serotonin, and finally he died of heart failure and bronchopneumonia. The primary site of this carcinoid tumor was of the bronchus of the right B10c , and it had large hepatic metastases. Electronmicroscopically, the tumor cells had secretory granules measuring 1500-3500 A in diameter. Immunohistochemically, the tumor cells were markedly positive for human chorionic gonadotropin (hCG) and antidiuretic hormone (ADH) and positive for serotonin, in both the primary site and hepatic metastases. Characteristic fibrous plaques were detected in the right atrium, tricuspid valve, right ventricle, and left atrium. Electron-microscopically, the fibrous plaques consisted of smooth muscle cells and myofibroblasts surrounded by basement membrane-like material. The abundant matrix of the fibrous plaques contained acid mucopolysaccharide, microfibrils and collagen fibers. The same fibrous plaques were also found in hepatic veins. Furthermore, retroperitoneal fibrosis was present, which showed proliferation of myofibroblasts, fibroblasts and immature mesenchymal cells.