pituitary carcinoma

Pituitary carcinoma is a malignant tumor confined to adenohypophyseal cells, demonstrating cerebrospinal or systemic metastasis. Pituitary carcinoma is often confused with invasive pituitary adenoma. Some pituitary carcinomas are invasive and can infiltrate the sella turcica and surrounding tissues, termed benign invasive pituitary adenomas, which are not included in the category of pituitary carcinoma. Due to the limitations of the definition of pituitary carcinoma, these malignant lesions are very rare, accounting for 0.2% to 0.5% of symptomatic pituitary tumors. Before 1998, approximately 98 cases of pituitary carcinoma were reported in the literature; from then until 2004, more than 40 additional cases were reported, and currently a total of about 150 cases have been reported. Pituitary carcinoma predominantly occurs in adults, can develop at any age, and shows no significant gender difference. The etiology of pituitary carcinoma remains unclear. Experts speculate that it may arise from the transformation of benign invasive pituitary macroadenomas, or it may be related to abnormal expression or mutation of certain cancer-related genes. Pituitary carcinoma can be divided into two groups based on its clinical course: most patients have varied clinical symptoms and long survival, distinguished from invasive pituitary adenomas only by multiple recurrences and distant metastasis; a minority of patients exhibit highly malignant biological behavior at the initial discovery of the tumor, such as extensive infiltration, repeated recurrences, and early metastasis. These patients often carry more genetic alterations and have an extremely poor prognosis, with survival of no more than 1 year after the appearance of metastatic lesions. The clinical manifestations of pituitary carcinoma can be broadly divided into two aspects: symptoms of local infiltration and compression, and symptoms of excessive pituitary hormone secretion.