Intra-suprasellar Rathke's cleft cyst: a case report and literature review

¹Departments of Neurosurgery, Hassan II Medical Center, Agadir, Morocco

^&Corresponding author
Dahmane Elhairech, Departments of Neurosurgery, Hassan II Medical Center, Agadir, Morocco

Introduction    

Rathke's cleft cysts are benign lesions formed from residue of the embryonic Rathke pouch. Usually located in an intrasellar or intra-suprasellar region. The pathogenesis of these lesions remains a subject of debate. Most often asymptomatic with fortuitous discovery on routine magnetic resonance imaging. Rarely these lesions can be symptomatic and engender a mass effect on surrounding structures, causing headaches, endocrine dysfunction, or visual disturbances. Because of their variable radiological features at computed tomography (CT) and magnetic resonance imaging (MRI), preoperative diagnosis can be difficult. Once the cyst is symptomatic, surgery remains the treatment of choice by endonasal endoscopic surgery, or by the conventional microsurgical technique.

Patient and observation     

Patient information: a 23-year-old girl presented with complaints of visual impairment, and headaches for 8 weeks prior.

Clinical findings: detailed neurological examination was normal. The visual fields (with Goldmann perimetry) revealed a bitemporal hemianopsia. The patient´s hormonal status was normal.

Diagnostic assessment: the preoperative MRI study of the sellar region, shown in Figure 1 (A,B,C,D,E), revealed a sellar and suprasellar lesion, hyperintense to brain on the T1-weighted image, with a slight enhancement of the outer border of the lesion, causing deformation of the adjacent optic chiasm and pressure effect on the third ventricule, which led to the provisional diagnosis of a cystic craniopharyngioma.

Therapeutic intervention: surgical removal of this lesion was felt to be indicated because a diagnosis could not be made otherwise in this young patient, and because compression of the optic chiasm was imminent causing her visual disturbance. A right pterional approach was chosen as the operative approach to this intra-suprasellar lesion. The Sylvian fissure was opened for exposure of the lesion, which was yellow, cystic, mostly avascular, and approximately 20 mm in diameter. Tissue fragments were fixed in 10% aqueous formalin. Examination revealed a single-cell layered, cuboidal epithelium and loose connective tissue. The final diagnosis was of a Rathke´s cleft cyst (Figure 2).

Follow-up and outcomes: the postoperative course was uneventful, the patient´s visual impairment and headaches are improved. The postoperative MRI study of the sellar region, shown in Figure 3(A,B,C,D), revealed gross-total resection of the tumor.

Discussion     

Rathke´s cleft cysts are well-delimited structures that vary in size from several millimetres to 1-2 cm [1]. Rathke´s cleft cyst (RCCs) are typically intrasellar, or intra and suprasellar, but may occur in an entirely suprasellar location with intact sella turcica. In the sella, Rathke pouch, formed during the fourth week of gestation, gives rise anteriorly to the adenohypophysis and posteriorly to intermediate lobe of the pituitary gland. In the suprasellar cistern, Rathke pouch gives rise to the pars tuberalis. If the normal involution of Rathke´s pouch fails to occur, the resulting RCC may increase in size by accumulation of cyst fluid and compress the surrounding structures, which can be symptomatic [2]. The median age of a patient diagnosed with symptomatic RCC is in the late 30s [3], with a female preponderance in the published series [4], but they have been reported in numerous pediatric patients [5], and as well as elderly patients in their 70s [3]. Asymptomatic RCCs are common incidental findings in 4-33% of autopsy cases and increasingly found on routine magnetic resonance imaging [6]. Rarely, these lesions can grow to become symptomatic, causing mass effect on surrounding structures, such as the pituitary gland, hypothalamus, and optic chiasm [7,8]. Comparisons of symptomatic and asymptomatic lesions have suggested that large size and suprasellar extension of RCCs may be associated with a greater tendency toward symptomatic presentation [1,3]. The typical symptoms include headache, endocrinologic dysfunction, or visual loss as our patient. In the published literature, headache was described in 44-81% of symptomatic cases [9], endocrinologic dysfunction in 30-60% of symptomatic cases such as hyperprolactinemia and growth hormone deficiency, or even diabetes insipidus, [10,11], and visual loss in 11-67% of symptomatic cases [12]. Intrasphenoidal RCC differs from intra-suprasellar RCC as it does not lead to visual loss or endocrinopathy [13]. Nearly all examples of RCCs with visual loss was due to a suprasellar extension [14].

The endocrinologic symptoms may differ depending on the age and gender of the patient. Men tend to suffer from hypogonadism, resulting in fatigue and decreased libido, while premenopausal women can present menstrual irregularities and galactorrhea, and postmenopausal women can present symptoms of panhypopituitarism, such as fatigue and altered mental status [15]. Diabetes insipidus is also a relatively common presenting finding in patients with RCCs, with reported rates ranging from 2.3% to 37% of patients [15]. Rathke´s cleft cysts are considered to be benign lesions. The smooth wall of an RCC is composed of a single-cell layer of cuboidal or columnar epithelium resting on a basement membrane [16]. Some RCCs exhibit inflammatory contents and squamous metaplasia, and this metaplasia is thought to be the reaction to chronic inflammation [17]. The fluid inside an RCC can vary, it can be clear, similar to cerebrospinal fluid with low protein content, in which case the cyst will rarely cause symptoms. Or it can be filled with mucinous fluid with high protein content, which is more frequently seen in symptomatic patients. During surgery, these lesions are frequently found to be yellow, waxy, solid masses [6]. The histological results are the same regardless of whether the RCC is intra- or suprasellar [16].

On MRI, RCCs will typically appear hyperintense on T2. However, their appearance on T1-weighted imaging can be either hyperintense, or hypointense [6]. Because of the variable signal intensities on MRI imaging, sometimes it´s difficult to distinguish RCCs from other saddle lesions. The main differential diagnosis of RCCs includes pituitary adenoma, pituitary cyst and cystic craniopharyngioma. The key feature distinguishing RCCs from an adenoma is the midline location of RCCs without stalk deviation, as well as the position of the cyst between the anterior and posterior glands when viewed from sagittal cuts [6]. It may not be possible to differentiate some RCCs from cystic craniopharyngiomas or pituitary adenomas with cystic components. Computer tomographic scans may sometimes reveal calcifications, suggesting the diagnosis of a craniopharyngiomas [18]. As a rule craniopharyngiomas (CPs), which are also thought to be derived from Rathke´s pouch occur in younger patients than RCCs [19]. However, for Shin et al. the age at initial surgery was almost the same for both, RCCs and Cps (37±14 years and 35±14 years, respectively) [20]. Rathke´s cleft cysts usually measure less than 10 mm in diameter, in another series, they ranged from 8 to 26 mm. While CPs tend to be larger when first detected, Radiologic examination of CPs typically reveals suprasellar location, calcifications, mural enhancement, and bony changes of the sellar confines. craniopharyngiomas unlike RCCs, tend to recur after partial excision and must, therefore, be removed in total.

The surgical indications of this condition include headaches, vision and visual field changes, enlarged cysts, pituitary endocrine diseases, and diagnosis uncertainty [7]. While indicating a need for surgical intervention, acute visual loss is considered an emergency. Partial resection of the wall and evacuation of cyst contents is the treatment of choice, in order to provide a symptomatic relief and to confirm the diagnosis. Further treatment such as postoperative radiotherapy or chemotherapy is not needed [17]. Some authors have supported the aggressive approach to remove the entire cyst wall despite the lower risk of recurrence and the higher rates of postoperative endocrine dysfunction. Endoscopic approach provides good lighting, with a large angle and close observation to distinguish the normal pituitary and the cystic wall. In addition, it results in reduced trauma, less complications, and quick postoperative recovery [7]. In intra-suprasellar RCCs, the endoscopic endonasal approach is considered the treatment of choice, while the transcranial approach has been indicated in cases of suprasellar location, or lack of resources [17]. Our surgical choice was based on the clinic, the young age, the surgeon's experience, the large volume of the cyst, and its important suprasellar extension.

Some authors have also described the technique of marsupialization, whereby after the decompression, the cyst wall is opened up widely and left open. Unfortunately, no study to date has compared the efficacy of marsupialization over simple decompression. The rates of permanent postoperative diabetes insipidus in series of cases treated with cyst drainage have been reported to range from 0 to 9% [4,9,15]. On the other hand, the rates of new-onset diabetes insipidus post aggressive approach are reported to be higher, ranging from 19% to as high as 69% [15]. The rates of cyst recurrence after surgical resection can vary, some studies report no recurrence [8], and some describe high rates, up to 42%.

Conclusion     

Rathke´s cleft cysts are frequently small benign lesions, asymptomatic and fortuitous discovery. Sometimes they can cause neuro-ophthalmological and/or endocrine disorders. Once the cyst is symptomatic, surgery remains the treatment of choice. The indication of craniotomie is replaced by the progression of neuroendoscopic techniques. Even a partial removal seems to be sufficient and provides good symptomatic relief, since recurrences occur with a low rate.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

Data collection: Dahmane Elhairech, Saloua Kanazy. Article revision and data analysis and interpretation: Dahmane Elhairech, Saloua Kanazy, Lmejatti Mohammed. All the authors read and approved the final version of the manuscript

Figures     

Figure 1: (A) coronal T2-weighted image; (B) axial T2 flair-weighted image; (C) and axial; (D) coronal, (E) sagittal, T1-weighted images demonstrate a large sellar and suprasellar cystic mass with a slight peripheral enhancement

Figure 2: photomicrograph of surgical specimen; the cyst wall possesses a single-cell layered cuboidal epithelium

Figure 3: (A,B,C,D) postoperative MRI images showed gross-total resection of the tumor

References