A 7-year-old girl is brought to the emergency department by her parents because of concerns that she is not growing and not developing appropriately. The parents say that the patient has cold intolerance, easy fatigability, and polyuria. A physical examination is notable for short stature and bilateral papilledema.Thyroid function tests are notable for low levels of triiodothyronine, thyroxine, and thyroid-stimulating hormone (TSH). An MRI shows an enhancing multilobulated suprasellar mass with ring calcification in the region of the sella turcica. If the lesion represents a primary intracranial neoplasm, which of the following is the most likely diagnosis?

Craniopharyngioma

10. The correct answer is A. Craniopharyngiomas account for 80%90% of neoplasms arising in the pituitary region and are the most common supratentorial tumor of childhood. They originate from squamous rest cells in the remnant of Rathkes pouch between the adenohypophysis and neurohypophysis. Eighty percent of patients have evidence of endocrine dysfunction at diagnosis; growth hormone deficiency is the most common (75%), followed by gonadotropin deficiency (40%), and ACTH or TSH deficiency (25%). Even though these masses are frequently large at presentation, it is rare for the pituitary stalk to be disrupted; only 20% of patients have prolactinemia, and 10%15% have diabetes insipidus (DI) secondary to pituitary stalk dysfunction. This patient has symptoms of growth hormone deficiency (short stature), biochemically documented hypothyroidism, DI (polyuria), and increased intracranial pressure as suggested by bilateral papilledema (nonspecific for craniopharyngioma). Imaging in craniopharyngioma may reveal calcification within the tumor. Answer B is incorrect. Ependymomas are most commonly found in the fourth ventricle and can result in hydrocephalus; however, it is very rare for ependymomas to cause the hormonal changes evident in this patient. Answer C is incorrect. Hemangioblastomas are associated with von HippelLindau syndrome when found with retinoblastomas. Such a tumor would not affect hormonal release. Answer D is incorrect. While a prolactinoma can cause many of the same symptoms (pubertal delay/failure) and may present with symptoms similar to those of a craniopharyngioma, it represents a far less likely diagnosis (accounting for 2.7% of childhood tumors) than craniopharyngioma. Answer E is incorrect. Thyrotropinomas present with hyperthyroidism without TSH suppression, goiter, visual symptoms, and headache. It would be uncommon for them to suppress growth hormone release, and they are very rare in childhood.