Cerebellar pilocytic astrocytoma

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● Often cystic, half of these have a mural nodule.

● Usually presents during the second decade of life (ages 10–20 yrs).

● A subtype of pilocytic astrocytoma. Formerly referred to by the nonspecific and confusing term cystic cerebellar astrocytoma.

Cerebellar pilocytic astrocytoma epidemiology.

see Cerebellar pilocytic astrocytoma in children.

Cerebellar pilocytic astrocytomas in adults should be treated with macroscopic complete surgical resection whenever possible. If this is achieved, long-term survival rates are excellent, whereas subtotal resection carries a high risk of tumor recurrence. Ki67 is less important prognostically than the extent of initial resection ¹⁾.

In the posterior fossa tumors, there is predominantly a mass effect with signs of raised intracranial pressure, especially when hydrocephalus is present. Bulbar palsy or cerebellar syndrome may also be present.

Cerebellar pilocytic astrocytoma diagnosis.

Cerebellar pilocytic astrocytoma differential diagnosis.

see Cerebellar pilocytic astrocytoma treatment.

Nine percent of the children in a study underwent repeated surgery due to progressive tumor recurrence, and 15% were treated for persistent hydrocephalus ²⁾.

The long-term functional outcome of low-grade cerebellar astrocytoma is generally favourable, in the absence of post-operative complications and brainstem involvement. No major impact of neurological deficits, cognitive functions and emotional disorders on academic achievement and independent functioning was observed ³⁾.

The good long-term outcomes suggest that it may be appropriate to do incomplete resection rather than risk additional neurological deficit ⁴⁾.

There is controversy about whether patients with tumor remaining after surgery should receive radiation therapy. It is also unclear whether only patients with incomplete resection require follow-up and for how long ⁵⁾.

Acute hemorrhagic presentation in pilocytic astrocytomas (PAs) has become increasingly recognized. This type of presentation poses a clinically emergent situation in those hemorrhages arising in PAs of the cerebellum, the most frequent site, because of the limited capacity of the posterior fossa to compensate for mass effect, predisposing to rapid neurological deterioration.

Complete resection of cerebellar astrocytoma is an important prognostic factor, indicating a more favorable prognosis than subtotal resection. This was also the conclusion of a much larger study by Villarejo et al. who reviewed 203 cases of low-grade cerebellar astrocytoma ⁶⁾.

Loh et al., documented that patients with subtotal removal of cerebellar astrocytoma can have arrested tumor growth or spontaneous tumor regression during long-term follow-up. Following partial resection of pediatric cerebellar astrocytoma, they recommend that the patients be followed up a “wait and see” approach with surveillance using MRI. They found that several tumors treated with radiotherapy after surgery had malignant transformation and do not recommend adjuvant radiation treatment for children with cerebellar astrocytoma who have subtotal resection. More research is needed on the prognosis of patients with subtotal resection of cerebellar astrocytoma ⁷⁾.

A subset may behave in a more aggressive fashion and clinically progress despite the use of conventional treatments. Histologic features associated with a more aggressive course include the presence of monomorphous pilomyxoid features (ie, pilomyxoid variant) and anaplasia in the form of brisk mitotic activity with or without necrosis ⁸⁾.

Cerebellar pilocytic astrocytoma case series.

Cerebellar pilocytic astrocytoma case reports.