Comprehensive Case Review of Juvenile Pilocytic Astrocytoma in a 5-Year-Old Girl with Gait Disturbance and Headache

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 Comprehensive Case Review of Juvenile Pilocytic Astrocytoma in a 5-Year-Old Girl with Gait Disturbance and Headache

Introduction

Juvenile pilocytic astrocytoma (JPA) is the most common pediatric cerebellar neoplasm and a subtype of glioma with typically indolent behavior. This expert-level column presents a comprehensive case of a 5-year-old girl presenting with headache and gait disturbance, ultimately diagnosed with JPA. We provide detailed radiologic-pathologic correlation, imaging features, diagnostic reasoning, differential diagnosis, and expert discussion on etiology, pathophysiology, epidemiology, clinical presentation, treatment, and prognosis of JPA.

Case Summary

A 5-year-old girl presented with a 1-month history of progressive gait abnormality and headache. A Head CT revealed a large heterogeneous mass in the posterior fossa with associated hydrocephalus. MRI showed a midline cerebellar mass with mixed solid and cystic components, peritumoral edema, loss of the fourth ventricle, upward transtentorial herniation, and mild tonsillar descent.

Imaging Findings

  • CT Brain: Posterior fossa mass with solid and cystic components, obstructive hydrocephalus, extensive edema, near-complete effacement of the 4th ventricle, transependymal CSF spread, and white matter hypoattenuation adjacent to the ventricles.

  • MRI Brain: Midline cerebellar mass with mural nodule, internal hemorrhage/calcification, peripheral rim enhancement, and mild layering hematocrit level. T1-hypointense and T2-hyperintense signal features noted. Compression of the brainstem and cerebellar tonsillar herniation were observed.

Figure 1. Non-contrast CT image showing a heterogeneously dense mass in the posterior fossa with hydrocephalus.

Figure 2. T2-weighted MRI showing mixed cystic and solid cerebellar mass with mural nodule.


Quiz

1. What is the salient abnormality? 

(1) Posterior fossa mass

(2) Aqueductal stenosis

(3) Pineal mass

(4) Infarction

2. What is the best description of the lesion on MRI? 

(1) Poorly defined

(2) Solid and necrotic

(3) Mixed cystic and solid

(4) Fat-containing

3. What is the most likely diagnosis? 

(1) Medulloblastoma

(2) Ependymoma

(3) Hemangioblastoma

(4) Pilocytic astrocytoma

Answer & Explanation

1. Answer: (1) Posterior fossa mass. Explanation: A large mass in the posterior fossa is the dominant finding on CT, consistent with a cerebellar tumor. 

2. Answer: (3) Mixed cystic and solid. Explanation: MRI reveals a heterogeneous lesion composed of both cystic and enhancing solid components, characteristic of JPA.

3. Answer: (4) Pilocytic astrocytoma. Explanation: The combination of a cystic mass with a mural nodule in a midline cerebellar location in a pediatric patient strongly suggests JPA.

Discussion

Etiology & Pathophysiology
Pilocytic astrocytoma is a WHO grade I glioma composed of bipolar cells with long hair-like (pilocytic) processes. These tumors exhibit a biphasic pattern with loose microcystic areas alternating with dense fibrillary regions. Rosenthal fibers and eosinophilic granular bodies are commonly seen. Tumors are typically slow-growing but may show accelerated growth in certain locations, particularly the optic pathway.

Epidemiology
JPA is the most common pediatric cerebellar tumor, representing ~85% of cerebellar astrocytomas in children and 10% of pediatric cerebral astrocytomas. It accounts for 0.6–5.1% of all intracranial neoplasms and 1.7–7% of all gliomas. It is commonly associated with neurofibromatosis type 1 (NF1), particularly in optic pathway tumors.

Clinical Presentation
Children may present with headache, nausea, vomiting, gait disturbance, blurred vision, diplopia, and neck pain, all of which relate to raised intracranial pressure and cerebellar dysfunction.

Imaging Features
CT often reveals a well-circumscribed, round or oval mass <4cm with cystic morphology and occasional calcifications. MRI typically shows T1 hypointensity and T2 hyperintensity. Four patterns are described: (1) cyst with mural nodule; (2) enhancing cyst wall with mural nodule; (3) central non-enhancing zone; and (4) solid mass without cystic components.

Treatment
Gross total surgical resection is the treatment of choice for cerebellar and cerebral JPAs and is often curative. For unresectable lesions or those in critical locations, stereotactic biopsy or subtotal resection may be performed. Radiotherapy is generally avoided due to the risk of long-term toxicity in children.

Prognosis
JPA has an excellent prognosis with 10-year survival rates exceeding 95% after gross total resection. Recurrence is rare with complete removal but may occur with subtotal resection. Tumors in the hypothalamic/optic pathway regions have higher recurrence potential.

References

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