Metastatic pancreatic neuroendocrine carcinoma causing Cushing's syndrome. ACTH secretion by metastases 3 years after resection of nonfunctioning primary cancer.

CONCLUSION: Following resection of a nonfunctioning neuroendocrine carcinoma of the pancreas, subsequent metastases, in the absence of a primary cancer (resected), developed the capacity to secrete ACTH and create the Cushing syndrome.
BACKGROUND: Although neuroendocrine carcinomas of the pancreas may produce one or more hormones and may switch secretion to a different hormone, no report is identified of a metastasis, in the absence of the primary tumor, developing de novo the capacity to secrete ACTH.
METHODS: A nonfunctioning islet cell carcinoma was resected and immunochemically stained for multiple hormones. Three years later hepatic metastases were partially resected and stained as before.
RESULTS: The primary cancer stained negative for ACTH and cortisol, positive for serotonin, and focally positive for gastrin. Three years later, after the development of a florid Cushing syndrome, the metastasis stained strongly for ACTH and negative for serotonin.