Rathke Cleft Cyst with T2 Hypointensity: MRI Features, Differential Diagnosis, and Evidence-Based Management

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Introduction

Rathke cleft cyst (RCC) is a benign, non-neoplastic epithelial cyst arising from remnants of Rathke’s pouch, located in the pars intermedia of the pituitary gland. While most RCCs are asymptomatic and incidentally discovered, certain imaging characteristics—particularly T1 hyperintensity combined with striking T2 hypointensity—represent a distinct and diagnostically important subtype.

This article presents a classic case of Rathke cleft cyst with T2 hypointensity, based on the attached MRI study of a 25-year-old woman with oligomenorrhea and mild hyperprolactinemia. Using this case, we comprehensively review the pathophysiology, epidemiology, clinical presentation, imaging features, differential diagnosis, diagnostic approach, treatment strategies, and prognosis, grounded in widely cited contemporary literature.

Pathophysiology of Rathke Cleft Cyst with T2 Hypointensity

Rathke cleft cysts originate from embryologic remnants of Rathke’s pouch, which normally involutes during pituitary development. Failure of complete regression leads to cyst formation between the anterior and posterior pituitary lobes.

The hallmark imaging feature in this case—T1 hyperintensity and T2 hypointensity—is attributed to highly proteinaceous or mucoid cyst contents. Elevated protein concentration causes:

  • Shortened T1 relaxation time → high T1 signal
  • Shortened T2 relaxation time → low T2 signal

This biochemical composition differentiates this RCC subtype from serous or CSF-like cysts and has significant diagnostic value.

Epidemiology

  • RCCs are identified in 13–22% of autopsy series
  • Peak detection in young to middle-aged adults
  • Slight female predominance
  • Most lesions are incidental
  • T2 hypointense RCCs are less common but well-described in neuroradiology literature

Clinical Presentation

Patient Summary (from attached case)

  • Age: 25 years
  • Gender: Female
  • Symptoms: Oligomenorrhea
  • Laboratory findings: Prolactin level 60 ng/mL

The mild elevation of prolactin (<100 ng/mL) is consistent with a stalk effect, caused by compression of the pituitary stalk, rather than autonomous hormone secretion.

Imaging Features (MRI-Based Diagnosis)

MRI is the gold standard for diagnosing Rathke cleft cysts.

Figure-Based Imaging Interpretation

Figure 1. Sagittal T1 Fat-Saturated MRI
A well-defined midline intrasellar cyst demonstrates high signal intensity on T1, consistent with protein-rich cystic content.


Figure 2. Sagittal T2 MRI

The lesion shows marked T2 hypointensity, a classic feature of proteinaceous Rathke cleft cysts.

Figure 3. Sagittal T2 MRI (Alternative Slice)
Persistent T2 hypointensity confirms the uniform internal composition of the cyst.

Figure 4. Sagittal T2 MRI
The cyst slightly expands the pituitary gland, without suprasellar extension or optic chiasm compression.

Figure 5. Sagittal T1 Contrast-Enhanced Fat-Saturated MRI
No internal enhancement is observed. A subtle enhancement of the cyst wall fold may be present.

Figure 6. Sagittal T1 Contrast-Enhanced Fat-Saturated MRI
The absence of solid enhancing components effectively excludes pituitary adenoma.

Figure 7. Sagittal T2 MRI
Posterior displacement of the T1 bright spot of the posterior pituitary gland is noted, a key distinguishing feature from adenomas.

Figure 8. Axial FLAIR MRI
The cyst remains hypointense relative to brain parenchyma, supporting a non-CSF, proteinaceous composition.

Key Radiologic Hallmarks of Rathke Cleft Cyst

  • Midline, pars intermedia location
  • T1 hyperintensity
  • T2 hypointensity
  • No or minimal rim enhancement
  • Posterior displacement of posterior pituitary bright spot
  • Mild pituitary stalk bowing
  • No cavernous sinus invasion

Differential Diagnosis

Entity

Key Distinguishing Features

Pituitary adenoma

Off-midline, solid enhancement, lateral displacement of stalk

Craniopharyngioma

Calcification, mixed cystic-solid components

Arachnoid cyst

Follows CSF signal on all sequences

Epidermoid cyst

Diffusion restriction

Hemorrhagic adenoma

Fluid-fluid levels, evolving signal

Diagnosis

Diagnosis of Rathke cleft cyst with T2 hypointensity is primarily radiologic. Clinical and laboratory findings support the diagnosis but are not definitive alone.

Key diagnostic elements include:

  • Typical MRI signal characteristics
  • Midline location
  • Lack of solid enhancement
  • Mild endocrine disturbance consistent with stalk compression

Treatment

Conservative Management

  • Asymptomatic or mildly symptomatic patients
  • Periodic MRI follow-up
  • Endocrine monitoring

Surgical Management

  • Indicated for:
    • Visual field defects
    • Severe headaches
    • Progressive endocrine dysfunction
  • Preferred approach: Endoscopic transsphenoidal drainage

Prognosis

  • Excellent overall prognosis
  • Low recurrence rate after surgery
  • Endocrine dysfunction may persist if chronic
  • Malignant transformation does not occur

Quiz

Question 1. A midline intrasellar cyst with T1 hyperintensity and T2 hypointensity most likely represents which lesion?

A. Pituitary adenoma
B. Craniopharyngioma
C. Rathke cleft cyst
D. Arachnoid cyst

Correct Answer: C
Explanation: Proteinaceous RCCs classically show T1 high and T2 low signal.

Question 2. Mild hyperprolactinemia (<100 ng/mL) in Rathke cleft cyst is best explained by:

A. Prolactinoma
B. Hypothalamic dysfunction
C. Stalk effect
D. Hormonal hypersecretion

Correct Answer: C
Explanation: Compression of dopaminergic inhibition causes mild prolactin elevation.

Question 3. Which MRI feature best differentiates Rathke cleft cyst from pituitary adenoma?

A. Intrasellar location
B. T1 hyperintensity
C. Lack of enhancement
D. Posterior displacement of posterior pituitary bright spot

Correct Answer: D
Explanation: Adenomas usually displace the bright spot laterally.

References

  1. Osborn AG, et al., Diagnostic Imaging: Brain, 3rd ed., Elsevier, 2020.
  2. Barkovich AJ, Pediatric Neuroimaging, 6th ed., Lippincott Williams & Wilkins, 2019.
  3. Trifanescu R et al., “Rathke’s cleft cysts,” Clin Endocrinol, vol. 76, no. 2, pp. 151–160, 2012.
  4. El-Mahdy W, Powell M, “Transsphenoidal management of RCC,” Neurosurgery, 2001.
  5. Kucharczyk W et al., “MR imaging of RCC,” Radiology, 1987.
  6. Bonneville JF et al., MRI of the Pituitary Gland, Springer, 2016.
  7. Zada G et al., “Surgical management of RCC,” J Neurosurg, 2011.

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