Pediatric Pineal Cyst Presenting as Headache: A Neuroimaging Case Study

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 Pediatric Pineal Cyst Presenting as Headache: A Neuroimaging Case Study

Case Summary

An 8-year-old boy presented with persistent headaches. Brain CT in the axial plane traversing the thalami and basal ganglia revealed a well-circumscribed, cylindrical low-density area (LDA) posterior to the third ventricle. The lesion was noted to compress the internal cerebral vein, suggesting the presence of a pineal cyst.

To further characterize the lesion and assess its relationship to adjacent neurovascular structures, contrast-enhanced MRI with sagittal and coronal reconstructions was recommended.

What Is a Pineal Cyst?

A pineal cyst is a benign, fluid-filled sac that develops within the pineal gland—a small, pine cone-shaped endocrine organ located near the center of the brain, just behind the third ventricle. These cysts are most often discovered incidentally during brain imaging performed for unrelated reasons, such as headaches or trauma. While typically asymptomatic and clinically insignificant, pineal cysts can occasionally enlarge and exert pressure on nearby structures. In rare cases, this mass effect may impair cerebrospinal fluid (CSF) flow, potentially resulting in symptoms such as headache, visual disturbances, or hydrocephalus.

DISCUSSION

1. Pathophysiology

Pineal cysts are formed by glial proliferation or degeneration of pineal parenchyma, and are lined by glial cells or flattened epithelial cells. The cysts may contain clear or slightly proteinaceous fluid with signal characteristics similar to cerebrospinal fluid (CSF).

In most individuals, the cyst is non-neoplastic and asymptomatic, but in rare cases, enlargement may result in compression of the quadrigeminal plate, tectum, or aqueduct of Sylvius, causing obstructive hydrocephalus.

2. Epidemiology

  • Prevalence: 1.5–4.3% in healthy adults; up to 10% in children undergoing MRI

  • Gender/age: More common in females and younger age groups

  • Incidental nature: Most cysts are asymptomatic and detected incidentally

  • Size threshold: Cysts ≥10 mm are often classified as giant pineal cysts, which are more likely to be symptomatic

3. Clinical Presentation

While most pineal cysts are asymptomatic, symptom-producing cysts may present with:

Symptom TypeClinical Features
Increased ICPHeadache, nausea, vomiting
Visual disturbancesDiplopia, visual field defects
CSF flow obstructionGait instability, hydrocephalus
Non-specific signsFatigue, difficulty concentrating

In our case, headache was the presenting complaint, likely due to venous compression or intermittent CSF flow disturbance.

4. Imaging Features

1) CT Findings:


  • Hypodense, well-circumscribed cystic lesion posterior to the third ventricle

  • No enhancement on post-contrast scans

  • Calcifications may be present in the pineal gland

2) MRI Findings:



  • T1-weighted: Isointense or hypointense compared to brain parenchyma

  • T2-weighted: Hyperintense (CSF-like signal)

  • Post-contrast T1: Typically shows rim enhancement only (no solid component)

  • Sagittal MRI is particularly helpful in evaluating aqueductal patency and tectal compression

MRI is the modality of choice to differentiate pineal cysts from pineal tumors, such as germinomas or pineoblastomas.

5. Treatment

Clinical ScenarioRecommended Management
Small, asymptomatic cystRoutine monitoring with periodic MRI
Symptomatic / ≥10 mm cystNeurosurgical consultation ± endoscopic fenestration
Cyst with hydrocephalusSurgical decompression or CSF diversion is required
Solid-enhancing lesionsFurther investigation for pineal neoplasm

Surgical intervention is rare and typically reserved for hydrocephalus, visual symptoms, or suspicion of malignancy.

6. Prognosis

  • Excellent in asymptomatic patients with stable imaging findings

  • Most cysts remain unchanged for years

  • Surgical outcomes are favorable in symptomatic cases

  • No evidence supports the malignant transformation of isolated pineal cysts

Quiz: 

1. What is the classic post-contrast MRI finding in a benign pineal cyst?

A. Homogeneous enhancement of the cyst
B. Heterogeneous solid enhancement
C. Rim enhancement of the cyst wall
D. Central calcification with intense enhancement

Explanation: Benign pineal cysts characteristically show no internal enhancement, with only the cyst wall enhancing after gadolinium administration.

2. Which scenario would most likely require surgical treatment of a pineal cyst?

A. Incidental cyst measuring 4 mm in a 30-year-old
B. MRI showing minor calcification of the pineal gland
C. Headache with compression of the cerebral aqueduct and hydrocephalus
D. Visual fatigue in the setting of a stable 6 mm cyst

Explanation: When a pineal cyst obstructs CSF flow, causing hydrocephalus, surgical decompression is warranted to alleviate increased intracranial pressure.

Conclusion

Pineal cysts are commonly incidental and benign, but careful evaluation is critical when they present with neurological symptoms such as headache or hydrocephalus. MRI plays a pivotal role in distinguishing benign cysts from tumors and guiding management decisions. Clinicians must remain vigilant in pediatric populations, where symptoms may be subtle but clinically significant.

References

  1. Al-Holou WN, Garton HJL, Muraszko KM, Maher CO. Prevalence of pineal cysts in children and young adults. J Neurosurg Pediatr. 2009;4(3):230-236. doi:10.3171/2009.4.PEDS0918

  2. Pu Y, Mahankali S, Hou J, et al. High prevalence of pineal cysts in healthy adults demonstrated by high-resolution, non-contrast brain MRI. AJNR Am J Neuroradiol. 2007;28(9):1706-1709.

  3. Barboriak DP, Lee L, Boyko OB, Friedman AH. MR differentiation of pineal cysts and tumors. AJNR Am J Neuroradiol. 1994;15(2):283-290.

  4. Klein P, Rubinstein LJ. Germinomas of the pineal region: a clinicopathological study. J Neurosurg. 1972;37(4):382–392.

  5. Osborn AG. Diagnostic Imaging: Brain. 3rd ed. Salt Lake City, UT: Amirsys; 2016.

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