Cushing's syndrome associated with a nested stromal epithelial tumor of the liver: hormonal, immunohistochemical, and molecular studies.

CONTEXT Ectopic ACTH syndrome (EAS) is principally associated with aggressive malignant tumors but also with neuroendocrine tumors of good prognosis. Recently, rare nonhepatocytic nested stromal and epithelial tumors (NSET) were characterized by their possible association with Cushing's syndrome of which biochemical and physiopathological features were still incompletely studied. OBJECTIVE To describe the clinical and hormonal characteristics of an EAS originating from a liver NSET and further understand the mechanism of cortisol overproduction. DESIGN AND SETTING This is a clinical case report from the Endocrinology Department of Caen University Hospital, France. PATIENT AND INTERVENTION A 17-year-old female patient was found to have a large liver NSET with mild Cushingoid clinical features and intense biological hypercortisolism but moderate ACTH secretion. Resection of the tumor was curative with a 30-month follow-up. RESULTS The epithelial component of the tumor coexpressed ACTH mildly, corticotropin-releasing hormone (CRH) strongly, and 11beta-hydroxysteroid dehydrogenase at a level comparable with normal human hepatocytes. CONCLUSIONS Liver NSET is a new cause of EAS, which may evoke hypercortisolism by multiple biochemical pathways.