recurrent pituitary tumor

  my father(age 52) had a transphenoidal surgery to remove a benign pituitary tumor in 1990. Yesterday a MRI showed that it has recurred. We did the test because of his having high blood pressure. No visual field loss is present as yet.
  My questions are:
  1. Does recurrence of a pituitary tumor imply malignancy?
  2. What are the ways of treating recurrent tumors surgery or radiation or both?
  3. What is proton beam radiosurgery?
  4. Are pituitary tumors invariably benign?
  5. He was doing thyroxine and other endocrine tests which were normal upto the last two months. Does this mean the tumor has grown in 2 months?
  please help!!
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Dear Sam,
There are many kinds of tumors that may present in the pituitary gland and in the region of the pituitary.  Most of these will be benign adenomas.  Some will secrete endocrinologically active substances that cause specific syndromes.  For example: growth hormone (acromegaly and gigantism), ACTH (Cushing's) and TSH (hyperthyroidism).  The progress of these patients mya be followed after surgery by getting blood levels of these hormones to follow for any endocrinological recurrence of the tumor.  Most adenomas do not secrete these substances and may be treated with surgery alone.  Few of these tumors are malignant.  
A recurrence of a pituitary tumor does not imply malignancy.  A tumor may become more aggressive and malignant, but this is unusual.  When a pituitary tumor recurs the options include repeat surgery, radiation and simple observation.  Surgery can be done through the nose (transsphenoidal) or via a formal craniotomy, depending on the location of the tumor.  The best way to treat a recurrent tumor depends on the location of the tumor and the pathology from the first resection.  
Proton beam radiotherapy is simply another means to deliver radiation to a small area of the brain.
Speak to your father's surgeon about the kind of tumor that was removed in the past and what the best option may be at this point for your father.  Ask lots of questions until you understand the situation and are comfortable with the care plan.
Good luck.