Pituitary Carcinoma in a Patient with Cowden Syndrome.

BACKGROUND Pituitary carcinomas are rare tumors that are histologically indistinguishable from pituitary adenoma. This report describes an extremely rare case of pituitary carcinoma in a patient with clinically diagnosed Cowden syndrome (CS). CS is a rare multisystemic hereditary disease with increase risks of cancer and benign overgrowth of different types of tissues. CASE REPORT A 52-year-old woman with history of CS presented with pituitary adenoma and multiple meningiomata. After surgical resection, there was recurrence of the pituitary tumor. Partial resection of the recurrent pituitary tumor revealed an adenoma. Radiotherapy was administered due to the histopathological aggressive features of the resected pituitary tumor and growth of the residual pituitary tumor on follow-up. Although the pituitary tumor shrank after radiotherapy, there was development of multiple new intracranial extra-axial lesions, including meningiomata. Resection of a rapidly growing extra-axial tumor in the parietal convexity region was performed. Given the similar histopathological features of the convexity tumor with the prior pituitary specimen, the diagnosis of pituitary carcinoma was established. A subsequent MRI scan showed metastatic deposits along the spine. The patient's condition deteriorated and she died shortly after the last surgery. CONCLUSIONS To the best of our knowledge, there is no prior report of pituitary carcinoma in a patient with CS in the literature. Pituitary carcinomas frequently spread within the craniospinal axis, in addition to hematogenous dissemination. Given the high risks of developing malignant tumors in patients with CS, multidisciplinary management including diagnostic imaging and close surveillance are of paramount importance in patient management.