A 14-year-old boy presents with 3 months of lethargy, headaches, and muscle weakness. His parents note that he drinks water excessively. His vital signs are normal. A 24-hour urine collection shows polyuria. The fasting blood sugar is normal. An X-ray film of the brain reveals suprasellar calcification. An autopsy specimen of a similar case is shown in the image. Which of the following neoplasms is the most likely cause of polyuria in this patient?
Answer : A Craniopharyngioma
Central diabetes insipidus is characterized by an inability to concentrate the urine, with consequent chronic water diuresis, thirst, and polydipsia.
The disease reflects a deficiency of antidiuretic hormone (ADH, arginine vasopressin), which is secreted by the posterior pituitary under the influence of the hypothalamus.
One fourth of cases of central diabetes insipidus are associated
with brain tumors, particularly craniopharyngioma.
This tumor arises above the sella turcica from remnants of Rathke pouch and invades and compresses adjacent tissues.
Destruction of the posterior lobe of the pituitary, the source of ADH,causes polyuria and diabetes insipidus.
This coronal section of the brain shows a large cystic tumor mass replacing the midline structures in the region of the hypothalamus.
The other choices do not occur in this location and are rarely associated with central diabetes insipidus.