NEURORADIOLOGY


 
Case 21 :  
A teenager presents with headaches and blurring of vision.
What is the diagnosis?

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Diagnosis
Craniopharyngioma

Discussion

Introduction
Craniopharyngiomas are intracranial tumors that are typically both cystic and solid in structure. They are the second most common intra-sellar tumors. They occur most commonly in childhood and adolescence and in later adult life after age 50 years. Craniopharyngiomas are usually not discovered until they impinge upon important structures around them, and are frequently quite large (over 3 cm) when detected. They are histologically benign tumors, but they have a tendency to become adherent to structures in and around the pituitary gland and pituitary stalk, including the optic nerves, optic chiasm, intracranial arteries and the brain itself. 
They are thought to arise from remnants of the craniopharyngeal duct or Rathke's pouch which are developmental structures related to the primitive gut.  Embryonic cells from an incompletely involuted craniopharyngeal duct or transformation of squamous cells in the lower infundibulum or anterior pituitary gland may give rise to a craniopharyngioma.

Symptoms
If it compresses the pituitary stalk or involves the area of the pituitary gland itself, the tumor can cause partial or complete pituitary hormone deficiency. This frequently results in growth failure, delayed puberty, loss of normal menstrual function or sexual desire, increased sensitivity to cold, fatigue, constipation, dry skin, nausea, low blood pressure, and depression. Pituitary stalk compression can also cause diabetes insipidus and may increase prolactin levels causing galactorrhoea. If the craniopharyngioma involves the optic tracts, chiasm, or nerves, then visual disturbances can result. Involvement of the hypothalamus, an area at the base of the brain, may result in diabetes insipidus.

Imaging Features
The characteristic CT findings of craniopharyngioma are a combination of hypodense areas representing cysts and focal hyperdense areas representing calcification. Calcification is less common in adults, compared to children. The cystic component is common and can be quite extensive; it is only when these tumors are solid and lack calcifiction and cystic areas that they are difficult to differentiate from pituitary adenomas.
On MR, the solid and cystic components are easily seen, with the solid component isointense to brain on all pulse sequences, and tumor calcification seen as a region of negligible signal intensity. The appearance of the cystic component varies, depending on its protein component.

Treatment
The initial treatment for a craniopharyngioma is usually surgery. The goal of surgery is to completely remove the tumor while improving or at least preserving pituitary, visual and brain function. When the tumor cannot be completely removed, radiation treatment generally offers some degree of tumor control and prolonged survival. Additionally, because of the tendency for craniopharyngiomas to recur, repeat MRIs or CT scans should be obtained at least once a year for the first several years after surgery or radiation therapy.

Net Links
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Dr. Ashok Raghavan, Manipal Hospital, Bangalore