Endocrine Abstracts

The majority of space-occupying lesions in the region of the pituitary are adenomas, but a substantial minority (c. 10%) are either non-adenomatous pituitary 'tumors', or are hypothalamic lesions. A useful clue is that primary pituitary adenomas only very rarely present with diabetes insipidus. In the case of a hypothalamic lesion, problems with appetite, thirst control and short-term memory can be therapeutically highly problematic. Apart from craniopharyngiomas, the most common abnormality is a Rathke's cleft cyst, which appears to be a developmental abnormality which has a characteristic histology, including ciliated columnar epithelium surrounding a cyst cavity containing proteinaceous material. Arachnoid cysts are not dissimilar, but contain CSF-like fluid within a layer of epithelium. Both are usually treated surgically, with cystic components sometimes requiring marsupialisation to prevent fluid reaccumulation, or occasionally radiotherapy. Meningiomas and astrocytomas are other intra-cranial lesion s which may present with hypothalamic syndromes; meningiomas often have a characteristic radiological appearance, while optic nerve and pilocytic gliomas are relatively benign.
Supra-sellar germinomas may secrete hCG and are of varied malignancy, but should be treated aggressively with full CNS and spinal MR imaging followed by chemo-radiotherapy. The very rare chordomas and chondrosarcomas usually arise from the clivus: they are very aggressive and relatively radioresistant, although radiosurgery may have a place in their therapy. Langerhans cell histiocytosis and neurosarcoidosis are inflammatory processes (although LCH may be form of malignancy) which may infiltrate the hypothalamus and may require radiotherapy for local control and/or chemotherapy/corticosteroids.
Finally, a pituitary mass lesion in a young person which has a particular predilection for causing ACTH deficiency is lymphocytic hypophysitis, often but not exclusively occurring peri-partum. In the older age-group, never forget the possibility of a pituitary metastasis, although the primary (mostly breast or bronchus) will usually be obvious: treatment is with both surgery and radiotherapy, when symptomatic.