The term pituitary tumour usually implies an adenoma arising from anterior pituitary tissue, but in fact some 25% of tumours in this region are not adenomas, and many of these arise from the para-sellar region or within the hypothalamus. One clue as to the non-adenomatous origin of such tumours is the presence of diabetes insipidus, which is almost never present with a primary pituitary adenoma. Some 1% of sellar masses are metastases, most often from the frequent primary sites (lung, breast and prostate, but including lymphomas which my be primary). Other major pathologies include lymphocytic and granulomatous hypophysitis (now sometimes seen arising from immunomodulatory therapy for cancer), craniopharyngiomas, arachnoid cysts, germinomas, Langerhans cell histiocytosis and neurosarcoidosis, and Rathkes cysts which may be primarily intra-or supra-sellar.
Endocrine assessment and replacement follow the guidelines for pituitary adenomas, but there may be additional problems involving the control of appetite, thirst, sleep-weight patterns, and body temperature regulation. Craniopharyngiomas in particular are associated with such changes, especially obesity, which may be exacerbated by radical surgery. There is some evidence that bariatric surgery can help in this situation, but adipsia can lead to profound problems which may become intractable and lethal. Poikilothermia requires careful attention to regulation of the environmental temperature.
Thus, while anterior pituitary defects associated with adenomas can generally be treated and may lead, according to recent studies, to a normal quality of life, such hypothalamic syndromes can be extremely difficult to manage. It is essential that any therapeutic modalities are considered in this light, and are not allowed to exacerbate such defects.