All are rare manifestations of carcinoid syndrome except:
Diarrhea is present in 68-84% at some time in the disease course. Diarrhea usually occurs with flushing. Steatorrhea is present in 67%. So steatorrhea is not a rare manifestation. Rare manifestations of Carcinoid syndrome includes retroperitoneal fibrosis causing urethral obstruction, Peyronie's disease of the penis, intraabdominal fibrosis, and occlusion of the mesenteric aeries or veins. Reference: Harrisons Principles of Internal Medicine, 18th Edition, Page 3062
Retroperitoneal fibrosis
Peyronie's disease of the penis
Occlusion of the mesentric aeries
Steatorrhea