Rathke’s cleft cysts (RCC) may occasionally present with symptoms of pituitary apoplexy, curiously in one small series only 2/6 had hemorrhage in the lesion at surgery so cause symptoms is uncertain.
Intralesional nodules help make the diagnosis of RCC and are believe to be due to mucinous material on histologic examination and cholesterol and protein on biochemical analysis. It has been suggested that the nodule is a concretion of material within the cyst and that the amount of protein in intracystic nodules influences MR signal intensity.
Demographics and clinical presentation
Rathke’s cleft cysts are typically asymptomatic and are found in 13-22% of autopsies. If large, they may cause visual disturbance due to compression of the optic chiasm or pituitary dysfunction due to compression of adjacent pituitary tissue and distortion of the pituitary stalk.
There appears to be a female preponderance with a female to male ratio of approximately 2:1.
Rathke’s cleft cysts are typically asymptomatic and are found in 13-22% of autopsies. If large, they may cause visual disturbance due to compression of the optic chiasm or pituitary dysfunction due to compression of adjacent pituitary tissue and distortion of the pituitary stalk.
There appears to be a female preponderance with a female to male ratio of approximately 2:1.
Pathology
Rathke’s pouch forms during the 4th week of embryologic development as a rostral outpouching from the roof of the primitive oral cavity. The anterior wall of the pouch gives rise to the anterior lobe of the pituitary (pars distalis). The posterior wall of the pouch does not proliferate and remains as the intermediate lobe of the pituitary (pars intermedia). The lumen of the pouch narrows to form a cleft (Rathke’s cleft) that normally regresses. Persistence of this cleft with expansion is believed to be the origin of a Rathke’s cleft cyst.
The wall of the cyst is typically lined by a single cell layer of epithelium, often containing goblet cells, and often ciliated.
Radiographic findings
On imaging a Rathke’s cleft cyst is seen as a well-defined non-enhancing midline cyst within the sellar arising between the anterior and intermediate lobes of the pituitary. 40% are purely intrasellar and 60% have suprasellar extension, and purely suprasellar location, although reported, is rare.
On CT it is typically non-calcified and of homogenous low density. Uncommonly it may be of mixed iso- and low density, or contain small curvilinear calcifications in the wall (seen in 10-15% of cases)
On MRI the signal characteristics vary according to the cyst content which may be mucoid or serous. On T1, 50% are hyperintense and 50% are hypointense. On T2, 70% are hyperintense and 30% are iso or hypointense. In 70-80% of cases a small non-enhancing intracystic nodule can be identified which is virtually pathognomic of a Rathke’s cleft cyst. When seen it is hyperintense to surrounding fluid on T1 and hypointense on T2. Depending on the signal of the surrounding fluid it may be inapparent on one or other sequence.
No contrast enhancement of the cys is seen, however a thin enhancing rim of surrounding compressed pituitary tissue may be apparent.
Rathke’s pouch forms during the 4th week of embryologic development as a rostral outpouching from the roof of the primitive oral cavity. The anterior wall of the pouch gives rise to the anterior lobe of the pituitary (pars distalis). The posterior wall of the pouch does not proliferate and remains as the intermediate lobe of the pituitary (pars intermedia). The lumen of the pouch narrows to form a cleft (Rathke’s cleft) that normally regresses. Persistence of this cleft with expansion is believed to be the origin of a Rathke’s cleft cyst.
The wall of the cyst is typically lined by a single cell layer of epithelium, often containing goblet cells, and often ciliated.
Radiographic findings
On imaging a Rathke’s cleft cyst is seen as a well-defined non-enhancing midline cyst within the sellar arising between the anterior and intermediate lobes of the pituitary. 40% are purely intrasellar and 60% have suprasellar extension, and purely suprasellar location, although reported, is rare.
On CT it is typically non-calcified and of homogenous low density. Uncommonly it may be of mixed iso- and low density, or contain small curvilinear calcifications in the wall (seen in 10-15% of cases)
On MRI the signal characteristics vary according to the cyst content which may be mucoid or serous. On T1, 50% are hyperintense and 50% are hypointense. On T2, 70% are hyperintense and 30% are iso or hypointense. In 70-80% of cases a small non-enhancing intracystic nodule can be identified which is virtually pathognomic of a Rathke’s cleft cyst. When seen it is hyperintense to surrounding fluid on T1 and hypointense on T2. Depending on the signal of the surrounding fluid it may be inapparent on one or other sequence.
No contrast enhancement of the cys is seen, however a thin enhancing rim of surrounding compressed pituitary tissue may be apparent.
Differential diagnosis
The main differential differential diagnoses are:
craniopharyngioma
no gender difference
similar age group
usually suprasellar or have a suprasellar component
cystic pituitary adenoma
arachnoid cyst
older patients
no gender difference
epidermoid cyst
usually suprasellar
restriction on DWI
The main differential differential diagnoses are:
craniopharyngioma
no gender difference
similar age group
usually suprasellar or have a suprasellar component
cystic pituitary adenoma
arachnoid cyst
older patients
no gender difference
epidermoid cyst
usually suprasellar
restriction on DWI
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