Ileal carcinoid tumor complicating carcinoid heart disease and secondary retroperitoneal fibrosis

A 70-year-old man with metastatic liver tumors showed carcinoid syndrome with clinical symptoms of facial flushing, palpitation, dyspnea, and an itching sensation. Regurgitation of the tricuspid and aortic valves was observed by echocardiography. An elevated serum level of serotonin and a high urine excretion of serotonin metabolites were confirmed. Autopsy confirmed a serotonin-immunoreactive 1 cm ileal carcinoid tumor with metastasis to the liver, bone and peritoneum. The tumor cells were argyrophilic but not argentaffin, and showed erythrophagocytosis in the primary lesion. All the four heart valves and bilateral atrial endocardium showed fibromyxoid thickening, indicating the association of carcinoid heart disease. Desmoplastic reaction with deposition of sulfated acid mucopolysaccharides was also observed in the retroperitoneal space (secondary retroperitoneal fibrosis). Stenosis of the bilateral ureters and inferior mesenteric artery provoked hydronephrosis and lethal ischemic necrosis of the left-sided colon, respectively. Rarity of functioning ileal carcinoid tumor and pathogenesis of systemic fibroplasia are discussed.