Pituitary adenoma is a benign tumor of an endocrine gland that is situated underneath the brain. Pituitary gland is connected to the brain and it produces several hormones. The most common type of pituitary tumor is one that secretes prolactin, hormone responsible for breast milk production. Women with this tumor usually have irregular periods and breast discharge. Pituitary adenoma usually does not cause headaches, unless it becomes large and compresses the brain. Most of the tumors are small and are called microadenomas and only rarely become large macroadenomas. A group of German researchers just published a study in Cephalalgia that looked at possible causes of headaches induced by pituitary adenoma. Fifty-eight patients with pituitary adenoma were analyzed. Twenty-four patients (41%) had tumor-attributed headache with seven having migraine-like headaches, 11 tension-type headaches, and three having both. Cluster headache-like headache was found once, and two headaches remained unclassified. Tumor-attributed headache was associated with a positive prior history of headaches, nicotine abuse, and a faster tumor growth. Whenever a woman with headaches has irregular periods or a milky discharge from her breast an MRI scan of her brain and a blood test for prolactin level must be obtained. If the tumor is allowed to grow large it can cause impairment and even loss of vision because of the compression of optic nerves. The treatment is usually with medication that shrinks the tumor and only rarely surgery is needed. This surgery can often be performed transnasally – through the nose with faster recovery than when it has to be done by opening the skull.