Craniopharyngioma

General characteristics

Craniopharyngiomas are benign tumours that usually present in childhood or early adulthood. Craniopharyngioma (WHO grade I) is a benign, partly cystic epithelial tumor of the sellar region, presumably arising from squamous cell rests within the pars tuberalis of Rathke’s pouch.

Two clinicopathological forms are distinguished: adamantinomatous and papillary.

Epidemiology

This type of tumor accounts for 1.2–4.6% of all brain tumors. The age incidence is bimodal; peaks are observed in children aged 5–14 years and in adults older than 50 years.

Clinical symptoms

Symptoms usually present in adolescence or early adulthood. In children the most common symptom is growth failure, and in adults sexual dysfunction in men and amenorrhoea in women. The tumour can present with hypopituitarism (25–40 per cent), diabetes insipidus (50 per cent), visual failure from pressure on the optic chiasm or optic nerves (40–70 per cent), raised intracranial pressure from hydrocephalus from obstruction of the third ventricle (20–40 per cent), or personality and memory problems.

Imaging and Location

The most common localization is suprasellar with an intrasellar component.

  • 30% extend anteriorly,
  • 23% extend into the middle fossa,
  • 20% extend into the retroclival area.

The tumour is usually a mixture of cysts and solid components, where the cysts contain thick fluid (like engine oil) containing cholesterol crystals. Skull radiography may demonstrate calcification in the suprasellar region, but MRI scan is the most valuable investigation. The sagittal and coronal scans provide invaluable information to the surgeon.

On imaging, craniopharyngiomas present as heterogeneous mass lesions with solid and cystic components (Rennert and Doerfler 2007; Pisaneschi and Kapoor 2005; Chong and Newton 1993). Cystic components are present in 85% of cases. The cysts contain cholesterol crystals in varying concentrations as well as keratin debris. This may explain the variable signal intensities observed on MRI examinations. Calcifications, which occur in 75% of cases, are better documented with CT than with MRI. While on CT most cystic lesions present with the typical low-density appearance, the MRI signal characteristics may vary. Depending on the content of the cysts, blood byproducts, cell debris, cholesterol or other crystals, the signal intensity can be increased or decreased both on T1- and T2-weighted imaging.

Differential diagnosis

Differential diagnosis includes meningioma, optic nerve glioma, teratoma, dermoid or epidermoid cyst, metastasis, or sarcoidosis.

Treatment

After correction of any endocrinopathy, definitive operation can be performed in relative safety. The mainstay of treatment is resection of the tumour, although this has to be tempered by its tendency to be adherent to surrounding structures. Total resection is frequently impractical and attempts at aggressive resection have resulted in high morbidity and mortality (up to 20 per cent) and recurrence rates of 30–40 per cent (Weiss et al. 1989; Wen et al. 1989; Yasergil et al. 1990).

Most authors suggest safe subtotal resection and either postoperative radiotherapy to the residual disease or radiotherapy at the time of recurrence, depending on the age of the patient (Weiss et al. 1989; Wen et al. 1989). Some still suggest attempted complete removal as the best approach (Yasergil et al. 1990).

There are no randomized studies of safe subtotal resection (± radiation therapy) versus maximum possible resection (± radiation therapy), and no randomized studies of early radiation versus delayed radiation. If radiation is given after resection, the usual advised dose is at least 5400 cGy. At recurrence, it is not uncommon to get enlargement of one of the cysts. Cystic recurrences can be treated by placement of a reservoir and aspiration of the cyst intermittently (Gutin et al. 1980).

A different approach is to instil 32P—a β-emitting isotope with limited penetrance. This has been reported to result in cyst regression in more than 80 per cent of cases, with good symptomatic relief (Pollock et al. 1995).

Prognosis

In a large series, 60–93% of patients had a 10-year, recurrence-free survival.

These tumors are benign in nature and grow slowly but they tend to recur. The most significant prognostic factor associated with tumor recurrence is the extent of surgical resection; lesions larger than 5 cm carry a worse prognosis. The recurrence rate is significantly higher after incomplete resection.

Twenty-year survival for craniopharyngioma approaches 60 per cent, but recurrence is common and morbidity is significant (Regine and Kramer 1992). Craniopharyngiomas probably have a better prognosis when diagnosed in adults than when diagnosed in childhood.



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