Malignant pituitary corticotroph adenomas: report of two cases and a comprehensive review of the literature.

Corticotroph pituitary carcinomas are tumors, defined by the presence of distant metastases that determine their poor prognosis. The diagnosis and therapy of malignant corticotroph adenomas remains a clinical challenge. The molecular mechanisms of malignant transformation of pituitary adenomas are unclear, although they are believed to arise in an adenoma-to-carcinoma sequence. We describe two cases of malignant Cushing's disease with metastases in liver and bone, respectively. The primary pituitary tumors were treated by a combination of radiotherapy and transsphenoidal surgery, but recurred several times in both patients. The time interval between the diagnosis of Cushing's disease and the discovery of metastases was 32 and 17 years, respectively. In the first case the patient died within 6 months after diagnosis of metastasis, whereas the second patient is alive at a follow-up of 2 years after the discovery of the metastasis. Furthermore, we reviewed all available cases of corticotroph pituitary carcinomas reported in the literature and analyzed their clinical features and therapeutical management. In conclusion, frequent relapses of Cushing's disease, aggressive growth of macroadenoma, Nelson's syndrome after adrenalectomy or persistently high ACTH levels should prompt the clinician to consider the possibility of pituitary corticotroph carcinomas.