A case of midgut carcinoid with breast metastasis and cellular localization of serotonin and substance P.

Abstract
A case of midgut carcinoid with breast metastasis is reported. Hepatic metastases stored large amounts of serotonin as demonstrated by the Falck‐Hillarp technique. Immunocytochemically serotonin and substance P, which may co‐exist in gut enterochromaffin cells, were demonstrated in separate populations of tumor cells both in the hepatic and mammary neoplasms.