Pituitary carcinomas have been reported to metastasize systemically and, less commonly, along the craniospinal axis. Metastatic lesions have been reported in the cerebral cortex, cerebellum, spinal cord, leptomeninges, cervical lymph nodes, liver, ovaries, and bone. The authors are unaware of any other examples of subependymal metastases of a pituitary carcinoma. We report such a case.
Pituitary carcinoma is rare, accounting for roughly 0.2%1,3-5 of all pituitary tumors, with approximately 140 cases reported in the literature. These tumors are associated with a very high mortality, with 66% of patients dying within the first year after diagnosis. Pituitary carcinomas are differentiated from invasive pituitary adenomas by the presence of non-contiguous craniospinal tumor deposits and/or distant systemic metastases. The majority (88%) of these carcinomas prove to be hormone secreting, with prolactin secreting tumors being the most common. Invasive carcinomas evolve from hormone secreting pituitary adenomas after a latency period. Pituitary carcinomas have a predilection for systemic spread. The rate of systemic metastasis approaches 71% for prolactin producing tumors and 57% for ACTH producing tumors. Thirteen percent of tumors demonstrate both systemic and craniospinal patterns of metastatic spread.