A 5-year-old boy is brought to the office by his parents for evaluation of "clumsiness." The patient's fine and gross motor development have been normal at prior visits, but he now frequently runs into doorways or corners of furniture while walking around the house. He has also begun drinking large amounts of water and urinating "all the time." Temperature is 37 C (98.6 F), blood pressure is 95/65 mm Hg, and pulse is 130/min. Physical examination shows dry mucous membranes and loss of peripheral visual fields. Laboratory results are as follows: CT scan of the brain (exhibit) reveals an abnormality. Which of the following is the most likely diagnosis?

Question

A 5-year-old boy is brought to the office by his parents for evaluation of "clumsiness."  The patient's fine and gross motor development have been normal at prior visits, but he now frequently runs into doorways or corners of furniture while walking around the house.  He has also begun drinking large amounts of water and urinating "all the time."  Temperature is 37 C (98.6 F), blood pressure is 95/65 mm Hg, and pulse is 130/min.  Physical examination shows dry mucous membranes and loss of peripheral visual fields.  Laboratory results are as follows:  CT scan of the brain (exhibit) reveals an abnormality.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d58b_5dd0_bc81_4d7344f1d990_MD0003_00 Craniopharyngioma is a benign, slow-growing tumor derived from epithelial remnants of Rathke pouch (within the pituitary stalk). The mass is located in the suprasellar region adjacent to the optic chiasm and can cause a variety of complications. Compression of the optic chiasm can lead to visual field deficits including bitemporal hemianopsia. Due to peripheral vision loss, patients often bump into the corners of walls or furniture, as in this case. In addition, pituitary stalk compression can cause multiple endocrinopathies. For example, growth hormone or thyroid-stimulating hormone deficiencies can present as growth failure and pubertal delay in children. The damaged pituitary is also often unable to produce or secrete adequate antidiuretic hormone, which causes diabetes insipidus. The classic symptoms of dehydration, polyuria, and polydipsia are seen in this patient due to inability to concentrate urine. Laboratory findings may include high-normal serum sodium and dilute urine. As with most intracranial tumors, craniopharyngiomas can present with headache secondary to compression of nearby structures or obstructive hydrocephalus. Diagnostic imaging with MRI and CT scan of a craniopharyngioma would show a suprasellar mass with cysts and/or calcification. This patient's CT scan shows these typical findings. craniopharyngioma (Choice B) Medulloblastomas typically arise from the cerebellar vermis and present with vomiting, headache, and signs of cerebellar dysfunction (eg, ataxia, dysmetria). Signs of pituitary hormone deficiency would not be seen. In addition, this patient's mass is in the sellar region. (Choice C) Meningiomas are typically extraaxial, benign tumors most commonly seen in adults. Although these tumors can calcify, a symptomatic parasagittal meningioma would cause hemiparesis and seizures. This patient's tumor is in the sellar region. (Choice D) Pituitary adenomas are benign neoplasms that secrete excess prolactin, resulting in galactorrhea and amenorrhea. They can also present with bitemporal hemianopsia. Unlike craniopharyngiomas, pituitary adenomas do not calcify. (Choice E) Similar to craniopharyngiomas, Rathke cleft cysts are derived from Rathke pouch remnants. If large, they can cause visual field defects and endocrinopathies, but Rathke cleft cysts are not associated with calcifications. Educational objective: Craniopharyngiomas are benign, slow-growing tumors found in the suprasellar region and typically appear calcified on neuroimaging. Presenting symptoms include bitemporal hemianopsia and signs of pituitary hormone deficiencies (eg, diabetes insipidus, growth failure). References: Craniopharyngioma. (http://www.ncbi.nlm.nih.gov/pubmed/24467716) Craniopharyngioma. (http://www.ncbi.nlm.nih.gov/pubmed/21819881)

A 5-Year-Old Boy Is Brought to the Office by His