Mitchell E. Geffner, MD

Disclosures

Cancer Control. 2002;9(3) 

In This Article

Causes of Acquired Hypopituitarism

The most concerning cause of acquired hypopituitarism is a tumor in the hypothalamic-pituitary region. The most common tumor that arises in this region in childhood is a craniopharyngioma. While craniopharyngiomas are derived from epithelial remnants of Rathke's pouch, the same tissue that forms the anterior pituitary gland, they are not usually found exclusively within the pituitary gland, but more likely they are confined to the suprasellar region or are found in both suprasellar and intrasellar locations.[14] The presenting symptoms are dependent both on the main location of the tumor and on the direction(s) that the tumor grows. For example, if the tumor grows downward, it may cause alterations in the anterior and posterior clinoid bones or in the floor of the sella turcica and/or compress the pituitary gland. If the tumor grows upward, it may compromise vision by effects on the optic nerves. While medical textbooks typically describe the most common visual change in patients with craniopharyngioma as "bitemporal hemianopsia" (loss of the outer visual fields of both eyes) due to compression of the optic chiasm, this rarely occurs so precisely. More likely is the development of "quadrianopsias," which are smaller, more irregular field cuts. If the tumor grows even farther upward beyond the visual tracts, it may block the third ventricle and cause obstructive hydrocephalus, leading to headaches, vomiting, and/or blurry vision (in association with papilledema). Craniopharyngiomas are benign tumors histologically, but they are often described as "geographically malignant" based on their location and ability to wrap around vital structures (eg, optic nerves) precluding complete surgical removal. As stated previously, tumors originating in the pituitary gland are uncommon causes of acquired hypopituitarism in children. However, any surgery to remove a tumor in the hypothalamic-pituitary region may lead to hypopituitarism if it is not already present.

Another cause of acquired hypopituitarism is radiation treatment of a cancerous tumor in the head or neck region. More specifically, the radiation that is required to cure the child's tumor may, of necessity, damage normal tissue in its path or beyond. When hypopituitarism ensues in this situation, it is usually the result of radiation-induced damage to the hypothalamus, as the pituitary gland is relatively resistant to radiation. Different hypothalamic-pituitary axes have different sensitivities to radiation. Doses as low as 18 Gy using conventional fractionation can interfere with GH dynamics; doses higher than 40 Gy can cause deficiencies of gonadotropins, TSH, and ACTH, while >50 Gy may cause hyperprolactinemia, especially among young women.

Other causes of acquired hypopituitarism in childhood include previous brain infection (encephalitis and/or meningitis), hydrocephalus (even without an underlying tumor), vascular abnormalities (such as a varix in the hypothalamic-pituitary area)[15] (Fig 2C), and major head trauma usually associated with a significant loss of consciousness.[16]

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