Discussion

Primary amenorrhea is defined as the absence of menarche by age 16 yr (1). The etiologies can be grouped into three categories based on the hypothalamic-pituitary-ovarian axis (HPO): hypergonadotropic, normogonadotropic and hypogonadotropic. Hypergonadotropic hypogonadism is seen with primary ovarian failure such as in Turner's syndrome. Normogonadotropic amenorrhea encompasses a variety of etiologies including anatomic abnormalities and chronic anovulation syndromes. Decreased gonadotropin secretion is noted in both functional and anatomic disorders of the hypothalamus and pituitary such as Kallmann's syndrome and isolated gonadotropin deficiency; it is also noted in association with anorexia, malnutrition, and exercise-associated amenorrhea.

In our patient, amenorrhea presented with arrested puberty. This is suggestive of a disorder within the HPO axis. Further testing is necessary to determine the etiology. A normal FSH level excludes ovarian failure. Patients with central causes for the amenorrhea typically have low to normal levels of gonadotropins (2). Relative gonadotropin deficiencies may be congenital or acquired. Acquired syndromes include histiocytosis X, inflammatory or vascular diseases, infections involving the central nervous system, trauma, and tumors. Therefore, it is obvious that a study for CNS lesions is an essential part of the evaluation of these patients. A thorough evaluation includes a neurologic exam, fundoscopic exam and imaging study. The introduction of CT scanning and MRI has minimized the value of plain skull films (3). Plain skull films may be helpful in identifying calcification, bony erosion, or hyperostosis (4). However, CT scans and MRI are required to exclude the presence of a mass lesion in the hypothalamic/pituitary area. Although less sensitive than MRI, the CT appearance of many tumors has been characterized and may, in many cases, be quite useful. MRI is highly sensitive and may detect small tumors that would be missed with CT scan. Further, its sensitivity for tumor enlargement and composition makes it an essential tool during conservative management of a brain tumor.

Craniopharyngiomas are benign tumors that occur in the suprasellar and hypotha-lamic-third ventricular region of the brain. They account for 1.2-4% of all intracranial tumors and 5-10% of all tumors in children (5). At the time of diagnosis, most patients present with endocrine dysfunction, visual disturbance or increased intracranial pressure. It is the most common neoplasm associated with HPO dysfunction and pubertal delay (2). Craniopharyngiomas affect reproductive function by compressing the hypothalamus, the portal system, and/or the pituitary gland. They are relatively slow-growing tumors. Therefore, endocrinologic manifestations of tumor growth may not be acute. Clearly then, it is essential to monitor tumor growth and pituitary function if no intervention is undertaken. The primary therapeutic management is surgical. These tumors, however, can be highly adherent to adjacent structures. Therefore, surgical procedures can be extremely challenging. Operative mortality can be as high as 10%. Surgical morbidity includes stroke, blindness, and permanent endocrine disorders. The majority of patients have permanent postoperative pituitary deficiencies (5). Radiotherapy is effective at shrinking tumor bulk and is often used in combination with surgical management (6). Typical dose requirements are approximately 5500 cGy and may result in significant morbidity. Reported side effects associated with radiation include learning disabilities, visual problems, hypopituitarism, and the development of secondary tumors (7). The patient presented did not have any life-threatening complications from her tumor. Therefore, conservative management was elected. Her headaches worsened and, although not clearly a result of the tumor, surgical management was contemplated. However, because the tumor was not enlarging on MRI and a surgical approach would require a major cra-niotomy, radiation therapy was performed.

A main management issue in this patient is hormone replacement. Because she is hypo-estrogenic, she is at significant risk for osteoporosis and cardiac disease. Estrogen replacement should begin slowly and gradually increased to mimic normal pubertal development. If estrogen is increased too rapidly, normal breast development will not occur. In the patient presented, estrogen is currently being maintained with 1.25 mg of conjugated equine estrogens. It is important to note that young hypoestrogenic women may require doses of estrogen replacement therapy (ERT) twice those administered to postmenopausal women in order to maintain libido and sexual satisfaction. Progestin therapy is essential to prevent endometrial hyperplasia. Although progestin is recommended every month, some studies indicate that less frequent administration is acceptable (8). To assure protection, the progestin should be administered for a minimum of 12 d per administration cycle (9). This patient is receiving 10 mg of medroxyprogesterone acetate for fourteen days every other month.

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