A 10-year-old boy presents with complains of headache and visual disturbances. Further enquiry reveals that in last 3-4 months he has gained weight and has been experiencing lethargy and muscle weakness. His parents have noted that he drinks water excessively.
His vital signs are normal. A 24-hour urine collection shows polyuria. The fasting blood sugar is normal. Imaging
Imaging revealed a cystic tumor at the base of the brain. The MRI shown in the image reveals intra and supra sellar mass compressing the optic chiasm. It is hypointense on T1 and hyperintense on T2, suggesting predominantly cystic component with mural nodule. After contrast it demonstrates a suprasellar predominantly cystic mass with peripheral enhancement.
The symptoms and imaging are suggestive of Craniopharyngioma.
Craniopharyngiomas are histologically benign neuroepithelial tumors of the CNS that are predominately observed in children. Peak incidence of childhood craniopharyngiomas occurs in children aged 5-14 years. These tumors arise from squamous cell embryologic rests found along the path of the primitive adenohypophysis and craniopharyngeal duct.
Pediatric craniopharyngiomas are believed to arise from cellular remnants of the Rathke pouch, which is an embryologic structure that forms both the infundibulum and anterior lobe of the pituitary gland. Types
There are two pathological types. 90% of Craniopharyngiomas are adamantinomatous (paediatric) and 10% are papillary. Pathology
Adamantinomatous type shows cystic spaces (filled with thick oily fluid high in protein, blood products, cholesterol), calcifications, and wet keratin. It consists of reticular epithelial cells that have appearances reminiscent of the enamel pulp of developing teeth.
Typically, the tumors arise within the sella or adjacent suprasellar space. Symptoms are caused by mass effects on adjacent normal intracranial structures such as visual pathways, pituitary gland, and hypothalamus. They can become quite large, obstructing cerebral spinal fluid (CSF) pathways and causing hydrocephalus and increased intracranial pressure that leads to headaches, nausea, and projectile vomiting.
Anterior extension to the optic chiasm can result in a classic bitemporal hemianopsia, unilateral temporal hemianopsia, papilledema, or unilateral/bilateral decrease in visual acuity.
Direct compression or destruction of the hypothalamus and pituitary stalk, may lead to growth hormone deficiency, thyroid-stimulating hormone deficiency, adrenocorticotropic hormone deficiency, antidiuretic hormone deficiency, and luteinizing hormone or follicle-stimulating hormone deficiency. This can present as clinically significant short stature, hypothyroidism, diabetes insipidus, and other signs of panhypopituitarism.
Hypothyroidism, growth hormone deficiency, and direct hypothalamic injury can contribute to obesity and weight gain.
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.
Precocious or delayed puberty is also associated with craniopharyngiomas. Treatment
Treatment is usually surgical. Radiotherapy is useful for incomplete resection. Surgical approach depends on the size and sellar vs suprasellar extent. Some lesions can be accessed via a transphenoidal approach, whereas others require a craniotomy.