[Intracranial metastasis of pituitary adenoma: a case report]

Growth hormone-secreting pituitary adenoma is usually benign, and distant metastases are extremely rare. A case of growth hormone-secreting pituitary adenoma with multiple dural metastases is reported. A 53-year-old male was initially admitted to our hospital complaining of visual loss, presenting a pituitary abnormal mass with suprasellar extension. At the initial surgery, transsphenoidal surgery was selected, and the histological finding was benign pituitary adenoma. Seven and 16 months after the initial surgery, second and third surgeries via a transcranium route were performed for recurrence of the pituitary tumor. Histological findings revealed an appearance similar to the initial tumor in both surgical specimens. After the third operation, radiation therapy (local irradiation: total; 44 Gy) was performed. Six years after the first surgery, three tumors were located in the right frontal, parietal convexity and cerebellar tentorium. The tumors were totally removed by 4th and 5th surgeries. Histological examination showed malignant transformation from the primary benign growth hormone-secreting pituitary adenoma, with dural metastasis. Immunohistochemical staining with MIB-1 antibody demonstrated a high index of 7%. The patient is still alive after more than one year since the diagnosis of distant metastasis. According to previous reviews, few patients have survived more than one year. We conclude patients with benign pituitary adenoma should be carefully followed up for fear of malignant transformation or dural metastasis.