Description
Rathke’s cleft cysts (RCCs) are benign, sellar or suprasellar lesions originating from the remnant epithelial lining of Rathke’s pouch, a component of embryonic development that gives rise to the anterior pituitary gland. They are often incidental findings and rarely symptomatic. Also known as a pars intermedia cyst.
Pathogenesis
Rathke’s cleft cysts arise from the persistent remnants of Rathke’s pouch. The pouch normally involutes during development, but when it fails to do so, its remnants can give rise to cysts.
Epidemiology, Risk Factors & Associations
- More common in females (2:1 ratio)
- Peak incidence in the 4th and 5th decades of life
- No established risk factors or associations
Clinical Features
Most RCCs are asymptomatic and found incidentally. When symptoms do occur, they can include headache, visual disturbance due to compression of the optic chiasm, and pituitary dysfunction due to compression and distortion of the pituitary tissue/stalk.
Complications
Complications can occur due to mass effect on surrounding structures, such as hypopituitarism and visual disturbances due to compression of the optic chiasm.
Pathological Features
Histopathology
- Macroscopic: Cysts are typically thin-walled and filled with clear or xanthochromic fluid. An intraluminal nodule, if present, may be adherent to the cyst wall or free-floating.
- Microscopic: Lined by a single layer of respiratory-typeciliated cuboidal or columnar epithelium with goble cells. The intraluminal nodule is composed of desquamated cellular debris.
Radiological Features
General Features
- Characteristically demonstrates a well-circumscribed cystic lesion in the sellar or suprasellar region, at the anterior margin of the neurohypophysis or infundibulum
- Intracystic nodule is present in up to 77% cases.
- No solid or nodular enhancement.
- Thin peripheral enhancement may result from compression of normal adjacent pituitary tissue or inflammation of the wall
- Typically non-calcified.
CT
- Non-contrast: Isodense to CSF. Non-calcified.
- Contrast-enhanced: No enhancement or minimal rim enhancement.
MRI
- T1: Variable. 50% are hyperintense (high protein content), 50% are hypointense. Intracystic nodule or dot T1 hyperintense.
- T2: Variable. Usually hyperintense (70%), 30% iso- to hypointense. May demonstrate hypointense rim. Intracystic nodule T2 hypointense.
- T1 C+: No enhancement or minimal rim enhancement (compressed pituitary tissue).
- DWI/ADC: No restriction.
Grading and Staging
There is no established grading or staging system for Rathke’s cleft cysts.
Diagnosis
Diagnosis is often made incidentally during imaging studies for unrelated conditions. Definitive diagnosis is made histologically following surgical resection, if performed.
Differential Diagnosis
- Cystic pituitary adenoma: Typically demonstrates enhancement and may have micro or macronodular growth patterns. May demonstrate septations. May demonstrate fluid-fluid levels or haemorrhagic debris. May be off-midline in location. Hormonal symptoms may be present.
- Craniopharyngioma: Tends to be more solid with a combination of cystic components. Calcifications are commonly present.
- Arachnoid cyst: Often located in the middle cranial fossa, tends to follow CSF signal in all MRI sequences. Usually seen in older patients.
- Epidermoid cyst: Usually suprasellar, diffusion restriction.
- Teratoma: Usually has solid component with fatty components.
Management
Most RCCs are asymptomatic and require no treatment. In symptomatic cases, surgery is often the preferred treatment. Recurrence may occur. Endocrinology consultation may be necessary for managing hormone imbalances.