H. ZAGHOUANI, N. EZZAIRI, A.BEN ABDALLAH,S. YAHYAOUI, S. MAJDOUB,T. RZIGUA, L. BEN CHRIFA,H. AMARA, D. BEKIR, CH.

KRAIEMDepartement of radiology, Hospital of Farhat Hached, Sousse,

Tunisia

NR37

Rathke’s cleft cysts (RCCs) are benign congenital, non-

neoplastic sellar and/ or suprasellar lesions originating

from epithelial remnants of Rathke’s pouch .

These cysts are extremely common, found during

routine autopsies in 13% to 22% of normal pituitaries.

In 1913, Goldzieher described the first case of RCC

as an incidental postmortem finding.

The description of RCC has expanded since the

advent of computed tomography (CT) scanning and

magnetic resonance imaging (MRI), showing that

the incidence of this disease wich discovery was

only by autopsy, was underestimated.

The aim of this work is to emphasize the value of MRI in

the positive and differential diagnosis of this disease

through a retrospective study of 5 cases of Rathke’s

cleft cyst with a literature review.

We retrospectively analyzed the records of five patients

with Rathke’s cleft cysts collected in the service of

radiology in the hospital of Farhat Hached Sousse.

 A brain MRI was performed for all patients. All the

cysts were discovered incidentally. 

There were two female and three male patients ranging

in age from 14 to 48 years.

MR examinations were performed using 1.5-T

imagers.

Axial and coronal T1-weighted images were obtained

without administration of gadolinium.

With axial and coronal FSE T2-weighted images.

Section thickness was 4 mm, with intersection spacing

of 0%.

The signal, shape, size, seat and reports of the lesions were

analyzed.

 It showed in all cases a cystic formation of the sellar

region with variable signals and sizes. 

The localization of the cysts was strictly intrasellar in 4

cases and extended to the suprasellar region in one case.

 Of the five MR scans reviewed, the lesions were of low

signal intensity in T1-weighted images, there was no

enhancement in post-gadolinium sequences .They were

recorded to be of high intensity T2-weighted images.

Coronal T1 MR image Coronal T1 MR image Coronal T2 MR image Coronal T2 MR image

Coronal postcontrast T1 MR image

Coronal postcontrast T1 MR image

Sagittal post contrast T1-weighted MR image

Sagittal post contrast T1-weighted MR image

Rathke’s cleft cyst (RCC) was first incidentally reported

by Lushka in 1860 as ‘an epithelial area in the capsule

of the human hypophysis resembling oral mucosa’.

The first symptomatic RCC case was described by

Goldzieher in 1913.

RCCs have been referred to by a variety of names

including pituitary cyst, mucoid epithelial cyst,

intrasellar epithelial cyst, Rathke’s pouch cyst, and

colloid cyst of the pituitary.

Not until 1934 did Frazier and Alpers propose its

contemporary name of tumor of Rathke’s cleft.

As Voelker and colleagues have stated, the most common

theory about the origin of RCCs is that the cysts are derived

from true remnants of the embryologic Rathke pouch.

On or about the 24th day of embryonic life, the Rathke pouch

arises as a dorsal diverticulum from the stomodeum; it is

lined with epithelial cells of ectodermal origin.

At approximately the same time, the infundibulum forms

as a downgrowth of the neuroepithelium from the

diencephalon.

By the fifth week, the Rathke pouch comes into contact

with the infundibulum, and the neck of the pouch

becomes occluded at the buccopharyngeal junction.

During the sixth week, the Rathke pouch separates from

the oral epithelium. Subsequently, the pars distalis of the

pituitary gland develops from the anterior wall of the

pouch.

The posterior wall does not proliferate and remains as the

poorly defined pars intermedia.

The residual lumen of the pouch is reduced to a narrow

Rathke cleft, which generally regresses. The persistence

and enlargement of this cleft is considered to be the cause

of the RCC.

Other authors have different theories regarding the

formation of RCCs, suggesting instead that the cells of

origin are derived from the neuroepithelium or the

endoderm, or that they come from metaplastic anterior

pituitary cells.

Rathke cleft cysts are smoothly marginated cysts that vary in

size from a few millimeters to 1–2 cm.

The contents vary from clear CSF-like fluid to thick mucoid

material.

Microscopically, they are similar to other endodermal cysts

(neurenteric and colloid). They are lined by pseudostratified

or single-layered columnar or cuboidal epithelium.

Cilia and scattered mucin-secreting goblet cells are

common. Many cysts have squamous differentiation,

and cornified squamous pearls are occasionally

identified.

The intracystic nodule consists of mucinous material at

histologic examination. Biochemical analysis of this

material is consistent with cholesterol and protein.

Forty percent are completely intrasellar, while 60%

have some suprasellar extension through the cleft of the

diaphragma sella .

Completely suprasellar cysts are rare .

RCCs often produce no symptoms and so are usually

discovered incidentally, when radiographic or necropsy

findings are reviewed.

Symptomatic RCCs are uncommon, but cysts can

enlarge and cause symptoms secondary to compression

of the pituitary gland, pituitary stalk, optic chiasm, or

hypothalamus.

Symptomatic RCCs vary in presentation: headache,

visual and/or endocrine disturbance.

MRI is the modality of choice in the detection of RCCs.

It is superior to CT scanning for evaluating RCC mass

extension.

Sagittal and coronal MRI scans provide reliable

information concerning the relationship of the mass to

the optic nerves, optic chiasm, and hypothalamus.

Coronal MRI is also helpful in the evaluation of the

lateral extension of the sellar cyst and its relationship to

the internal carotid arteries and cavernous sinuses. MRI

also has superior multiplanar capabilities and contrast

resolution compared with those of CT scanning.

The advantage of CT scanning is that it is superior to

MRI in depicting small amounts of calcium.

This advantage can be important, because the presence

of calcification tends to indicate an alternative

diagnosis, such as craniopharyngioma, although small

calcifications are observed in some cases of RCC. CT

scanning is also superior to MRI in the evaluation of

associated bony remodeling.

Rathke cleft cysts (RCCs) frequently appear as well-

circumscribed, hypo-attenuating, cystic sellar masses

that may have suprasellar extension.As a result of the

different cystic contents, RCCs may appear iso-

attenuating or hyperattenuating relative to the brain

parenchyma.

RCCs usually have a thin wall that may enhance.

Variability in CT scan contrast enhancement among

individual cysts may reflect squamous metaplasia in the

wall or a peripherally displaced rim of pituitary tissue.

Extravasation of cystic contents may inflame nearby

structures, resulting in enhancement.

Calcification characteristically is not depicted on CT

scans, although Shin and colleagues have described this

finding in a number of cases.Complex cysts may have

septations.

Large cysts may cause bony remodeling.

The best imaging clue is a non enhancing non calcified

intra- and/or suprasellar cyst with an intracystic nodule .

While this is the typical picture, the imaging

characteristics vary widely.

Approximately half are hyperintense on T1- weighted

images, while half are hypointense. On T2-weighted

images, 70% are hyperintense and 30% are iso- or

hypointense.

Although no characteristic MRI features have been

identified, many RCCs are in 1 of the following 2

groups:

• Rathke cleft cysts (RCCs) with low signal intensity on

T1-weighted images and high signal intensity on T2-

weighted images.

• RCCs with high signal intensity on T1-weighted images

and variable signal intensity on T2-weighted images.

The cystic contents of the first group resemble those of

cerebrospinal fluid (CSF). In the second group, an

increase in the signal on T1-weighted images has been

related to the high content of mucopolysaccharides, which is

believed to result from an increase in the number of mucin-

secreting cells in the cyst wall, as well as from an increase

in the activity of these cells.

Uncommon cases with high signal intensity on T1-weighted

images and low signal intensity on T2-weighted images

have been suggested to result from a combination of

factors, including the presence of mucopolysaccharides,

chronic hemorrhage, a high cholesterol content, and

cellular debris from the cyst wall.

A small nonenhancing intracystic nodule is considered a

virtually pathognomonic sign of a Rathke cleft cyst.

These nodules show high signal intensity on T1-

weighted images and low signal intensity on T2-

weighted images, and they do not enhance.

Rathke cleft cysts do not enhance after contrast material

administration, although an enhancing rim of displaced

compressed pituitary gland is present in approximately

half of the cases.

The report's authors went on to conclude that, with

regard to RCCs, DWI-SSFSE with apparent diffusion

co-efficient (ADC) values provides objective

information for differentiation from other sellar cysts.

DWI-SSFSE with ADC values can also be employed in

the differentiation of RCCs from craniopharyngiomas

and hemorrhagic pituitary adenomas. All the RCCs are

hypo-intense relative to the normal brain parenchyma

(restricted diffusion) .

The differential diagnosis for Rathke cleft cysts includes

craniopharyngioma, cystic pituitary adenoma, or other

non neoplastic cysts (arachnoid cysts or

epidermoids) .

Unlike Rathke cleft cysts, craniopharyngiomas typically

demonstrate calcification and approximately 90% have

nodular, globular, or rim enhancement.

The presence of solid enhancing nodules in the cyst wall

also favors the diagnosis of craniopharyngioma.

The rare noncalcified cystic nonenhancing

craniopharyngioma, a finding more common in adults

than in children, may be impossible to distinguish from

Rathke cleft cyst with imaging findings alone.

The most common approach in the treatment of RCCs is

transsphenoidal surgery, in which the cyst is partially

excised and drained. 

This method is effective and helps to preserve pituitary

function.

Radical excision can cause additional and unnecessary

pituitary damage; therefore, it is not the treatment of choice.

In transsphenoidal surgery, the cyst is opened, a biopsy

specimen is obtained from the wall, and the cyst is drained

into the sphenoid sinus.

An interesting aspect of treatment is the decrease in the

size of the cyst after high-dose steroid therapy.

Although the pathophysiologic mechanism is not clear,

the steroids are assumed to have an effect on the

secretion or absorption of cystic fluid. This finding

suggests that steroid therapy may be useful in some

patients with an RCC and inflammatory changes.

Further study in this area is needed to gauge its

effectiveness is the treatment of RCCs.

The MRI is effecticient in the positive and especially

the differential diagnosis of these cysts, and to guide the

therapeutic decision.Once the diagnosis

is considered, a spaced clinical and MRI monitoring is

adopted in cases of asymptomatic cyst, while a surgical

treatment is proposed for the rare symptomatic cysts.