Adrenocorticotropin-producing pituitary carcinoma with liver metastasis.

We report here the extremely rare case of a twenty-eight year-old woman with a metastatic ACTH-secreting pituitary carcinoma. This is the thirteenth case to be described in the literature. Ten years ago Cushing's disease was diagnosed. After pituitary surgery, then bilateral adrenalectomy, a Nelson's syndrome appeared. The particularly extensive pituitary secondary development led to several pituitary surgical procedures, radiotherapy, and octreotide treatment. Eight years after Cushing's disease was diagnosed, liver tumors were discovered. Pathological examination and ACTH immunostaining demonstrated the secretory nature of these metastases. The lack of ectopic tumor, the LPH/ACTH equimolar ratio and a study of the plasma proopiomelanocortin derivatives by HPLC showed that the ACTH secretion originated in pituitary tissues (in situ and liver metastases). The processing of POMC seems thus to be normal in this kind of tumor and metastases. Intact POMC levels were very high, indicating an aggressive tumor, and ACTH/LPH production was paradoxically stimulated by octreotide. This case is also exceptional because of the slow development of the disease, which may be due to the complementary hepatic chemoembolization treatment.