Pituitary tumors are generally adenomas which arise from chromophobe or chromophil cells of the pituitary. These tumors arise within the sella turcica and produce its enlargement as they grow big leading to its erosion. Depending on the location of it pressure effects result.
On the basis of the size, Pituitary tumors have been classified into four groups (HARDY classification) Stage I tumors are micro adenomas (less than 10 mm in diameter) that may cause hormonal over secretion without producing structural problems or hypopituitarism.
Stage II consists of macro adenomas (greater than 10 mm in diameter) with or without suprasellar extension. Stage III is macro adenomas which invade the floor of sella producing sellar enlargement and suprasellar extension. Stage IV are invasive macroadenomas with diffuse destruction of the sella with or without suprasellar extension.
Pituitary tumors produce pressure effects on structures which lie near to the pituitary fossa. Optic chiasma is invariably involved in 90 per cent of patients. Bitemporal hemianopsia is the commonest visual defect. A small percentage may develop complete loss of visioin in one eye with a temporal defect in the opposite eye.
Endocrine disturbances are associated with pituitary tumors. The most common secretory pituitary tumors are prolactinomas and these cause glactorrhea and hypogondism. Growth hormone (Gil) secreting are the next most common form of tumors which cause acromegaly and gigantism. Next in frequency are cortico trophin. Secreting adenoma (ACTH secreting) which cause cushings disease.
Clinically, patient of pituitary tumor presents with headache which is referred to various parts of skull. When invasion of hypothalamus occurs there is abnormal temperature regulation, loss of consciousness and hormonal disturbances. Acute hemorrhagic infarction of pituitary adenoma results in a condition called pituitary apoplexy, resulting in severe headache, vomiting and loss of consciousness. This condition is found in patients with somatotroph or corticotroph adenomas.
Treatment of pituitary tumors is by medical, surgical and radiation. Bromocriptine is the dmg of choice for patients with microprolactinomas. If symptomatic, hyperprolactinemia gives inadequate response to the drug, then either surgery or radiation therapy is considered.
Somatostatin analogue octreotide is the adjunctive therapy in cases with acromegaly. Transphenoidal surgery of pituitary micro-adenoma is safe and also corrects hormonal over secretion. Morbidity with this procedure is less than 2%.
Radiation therapy is another method of treating pituitary tumors. Therapy consists of delivery of 4500 rad over 4 to 5 weeks, using rotational technique. Complications include production of Hypopituitarism in about 50% of patients.
Secondaries from primary growths elsewhere in the body produce metastatic growths in the various parts of the brain. Common sites of primary are lungs, Breast, kidney and G.I. Tract. Secondary growths are usually multiple and are rapidly growing. Symptoms shall depend on anatomical site involved. Many times tumors cells infiltrate the dura at the base of the skull and spread into leptomeninges. Blood malignancies (leukaemias and lymphomas) also invade the central nervous system.
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