Disseminated rectal carcinoid tumor with production of immunoreactive motilin.

This report presents a patient with a rectal carcinoid tumor of small size ( 14 mm in diameter), with typical growth pattern, localized in the mucosa. Despite these microscopically good prognostic features the patient died from metastatic disease 30 months later. The tumor had an unusual hormone profile with main secretion of immunoreactive motilin and serotonin. Immunocytochemically these substances were localized in separate tumor cell populations; the majority of tumor cells were motilin-immunoreactive and a minority were serotonin-immunoreactive. The patient was first treated interventionally by hepatic arterial embolizations and later medically with octreotide. The treatment resulted in long periods of good palliation related to reduced levels of tumor markers and weight gain. The plasma concentrations of motilin were analyzed with a N-terminal-specific assay before and during treatment.