Diagnostic Significance of Intracystic Nodules on MRI in Rathke's Cleft Cyst

Accurate preoperative diagnosis of a Rathke cleft cyst with the aid of a novel classification for sellar cystic lesions and a diagnostic algorithm decision: Tools for differentiating cystic sellar lesions with a representative case

Background

Rathke's cleft cyst (RCC) is a benign lesion in the sellar and suprasellar compartments. Similarly, pituitary adenomas can present with cystic morphology, making it a differential diagnosis when evaluating a patient with a cystic lesion in the sellar region. Surgical goals differ between RCCs and pituitary adenomas as the first can achieve remission of symptoms with cyst decompression in contrast to pituitary adenomas where complete resection would be the main goal. Imaging analysis alone may not be sufficient to define a preoperative surgical plan. The combination of imaging and conjoined use of validated tools may provide valuable insights to the clinician when defining a surgical approach.

Case Description

We present a case of a 27-year-old male with a 3-month history of visual disturbances and headaches. Magnetic resonance imaging showed a cystic lesion in the sellar compartment with compression of nearby structures. The authors were able to accurately diagnose this sellar lesion as an RCC with the conjoined aid of two classifications proposed in the literature. Cyst evacuation was performed with relief of symptoms and improved visual outcomes at follow-up.

Conclusion

While cystic adenomas can require total resection for cure, RCCs can show marked improvement with partial resection and evacuation of its contents. An accurate preoperative diagnosis can lead the surgeon to opt for the best surgical approach.

Approach to the Patient: Differential Diagnosis of Cystic Sellar Lesions

Cystic lesions arising in the sellar region are not uncommon and encompass cystic pituitary adenomas, Rathke cleft cysts, craniopharyngiomas, and arachnoid cysts. Their clinical presentation may be similar, including headache, visual field defects, and anterior pituitary hormone deficits, which makes differential diagnosis challenging. On the other hand, imaging features may indicate certain pathologies. In this approach to the patient, we describe the case of a patient who presented with right temporal hemianopsia and a sellar/suprasellar cystic lesion, which was determined to be Rathke cleft cyst. We discuss the imaging characteristics that may suggest a particular diagnosis between Rathke cleft cyst, cystic pituitary adenoma, craniopharyngioma, and arachnoid cyst and propose a flowchart for aiding in the imaging differential diagnosis.

Primary Tumors of the Pituitary Gland: Radiologic-Pathologic Correlation

Primary tumors of the pituitary gland are the second most common histologic category of primary central nervous system tumors across all age groups and are the most common in adolescents to young adults, despite originating from a diminutive endocrine gland that is often described as "about the size of a pea." The vast majority of these represent primary tumors of the adenohypophysis, specifically pituitary adenomas, which can be either functional or silent with regard to hormone hypersecretion. According to the fourth edition of the World Health Organization classification of endocrine tumors, published in 2017, cellular lineage and immunohistochemical stains for pituitary hormones and/or transcription factors help with making the correct pathologic diagnosis. From a radiologic standpoint, microadenomas pose challenges for accurate detection and avoiding false-negative or false-positive results, while macroadenomas pose challenges from local mass effect on surrounding structures. Pituitary carcinoma and pituitary blastoma also arise from the adenohypophysis and are characterized by metastatic disease and infantile presentation, respectively. While primary tumors of the adenohypophysis are common, a second category comprising primary tumors of the Rathke pouch (ie, craniopharyngioma) are uncommon, and a third category comprising primary tumors of the neurohypophysis (eg, pituicytoma) are rare. The authors review all three categories of pituitary tumors, with emphasis on radiologic-pathologic correlation, including the typical neuroimaging, histologic, and molecular features that may point toward a specific diagnosis. Work of the U.S. Government published under an exclusive license with the RSNA.

Ophthalmic Manifestations of Rathke's Cleft Cyst and Its Association to Radiological Characteristics

PURPOSE

To evaluate the ophthalmic features of Rathke's cleft cyst (RCC) and its association with radiological characteristics.

METHODS

In this retrospective single-center study, patients who showed typical findings suggestive of RCC on magnetic resonance imaging (MRI) and underwent relevant ophthalmic examination were recruited retrospectively. Patients were stratified into two groups according to the presence or absence of ophthalmic symptoms related to RCC. We reviewed patients' demographic information, initial symptoms, endocrinological status, ophthalmic features, and characteristics of MRI. Height, size and location of RCC, as well as the optic chiasm displacement assessed from MRI.

RESULTS

Thirty-three patients (20 women and 13 men) were included in this study from among 335 patients with RCC on MRI. Fifteen patients had ophthalmic manifestation related to the cyst (Ophthalmic group), whereas 18 patients were not (Non-ophthalmic group). Headache was the most common initial symptom (15 patients, 45.5%), followed by visual disturbance (7, 21.2%), diplopia (1, 3.0%), retro-orbital pain (1, 3.0%), galactorrhea (1, 3.0%), and peripheral extremity discomfort (1, 3.0%). In seven asymptomatic patients (21.2%), the lesion was an incidental finding during a regular medical examination. Ophthalmic manifestation included visual field defect (14 patients, 93.3%) and diplopia (1 patient, 6.7%). The height, volume, and the coronal and sagittal displacements were larger in the ophthalmic group (P < .001, all). Eleven patients who manifested ophthalmic symptoms underwent excision surgeries and nine of them (81.8%) experienced visual function improvement.

CONCLUSION

Appropriate ophthalmic examinations are warranted in patients with RCC, and treatment should be actively considered in patients with ophthalmic manifestations.

Rathke Cleft Cysts with Apoplexy-Like Symptoms: Clinicoradiologic Comparisons with Pituitary Adenomas with Apoplexy

BACKGROUND

Rathke cleft cyst (RCC) can cause acute symptoms mimicking pituitary adenoma (PA) apoplexy. We evaluated the clinicoradiologic features for distinguishing RCC from PA apoplexy.

METHODS

We retrospectively evaluated 22 patients with RCC and 24 patients with PA with apoplexy-like symptoms who underwent surgery via a transsphenoidal approach between November 1999 and December 2016. We compared the clinical data and magnetic resonance (MR) images between the 2 groups.

RESULTS

The RCC group was younger and had smaller tumors compared with the PA group (P = 0.02 and 0.001, respectively). The incidences of visual deficits and cranial nerve palsy were lower in the RCCs than in the PAs (P ≤ 0.02 for all). MR images showed more frequent intracystic nodules in the RCCs (P < 0.001), whereas nodular enhancement and lateral deviation of the pituitary stalk were more commonly seen in the PAs (P ≤ 0.003 for both). However, the presence of endocrine dysfunction or decreased consciousness, and the recurrence ratio, were not significantly different between the groups (P ≥ 0.48 for all). In the multivariable logistic regression analysis, patients without nodular enhancement had a 15.84-fold greater risk of RCC than did those with nodular enhancement (P = 0.031). The probability of RCC decreased 0.59-fold with each 1-cm³ increase in tumor volume.

CONCLUSIONS

RCC with apoplexy-like symptoms has different clinicoradiologic features compared with PA apoplexy. Patients with RCC present with milder ocular symptoms and smaller tumor volumes compared with those with PA apoplexy. The absence of nodular enhancement on MR images could suggest RCC.

MRI and pathological features of Rathke cleft cysts in the sellar region

The aim of the present study was to investigate the MRI and pathological features of Rathke cleft cysts (RCC) in the sellar region. A total of 45 RCC cases were retrospectively analyzed. RCC size, location, intracyst nodules and general signals, as well as the posterior pituitary bright spot (PPBS) were analyzed using MRI-T1 weighted images (T1WI) and T2WI. The relationship between the presence of PPBS and histopathological features was additionally evaluated. On T1WI, there were 18 cases of isointense signal, 16 cases of hyperintense signal, 9 cases of hypointense signal, 1 case of heterogeneous signal and 1 case with a stratification effect, with isointense signal in the upper part and hyperintense signal in the lower part. On T2WI, there were 5 cases of isointense signal, 27 cases of hyperintense signal, 11 cases of hypointense signal and 1 case of the stratification effect. There were 10 cases of PPBS+ and 35 cases of PPBS-. There were no significant differences in the age, sex, cyst location and size between PPBS+ and PPBS- cases. However, PPBS+ cases had significantly lower inflammation than PPBS- cases. A total of 20 cases of intracystic nodules were identified on MRI scans, most of which exhibited T2 -hypointense signals. The shape of RCC nodules varied and there were 17 cases where the nodules were non-adherent to the cyst wall. The MRI signals of RCCs varied and most nodules were floating within cysts. Intracystic nodules are characteristic features of RCCs when observed by MRI and thus are of high diagnostic value. Most patients with RCC were also PPBS-, which may be associated with an increased inflammatory response.

Fluid-fluid level on magnetic resonance images may predict the occurrence of pituitary adenomas in cystic sellar-suprasellar masses

The aim of the present study was to evaluate the value of identifying fluid-fluid level via preoperative magnetic resonance (MR) images in differentiating pituitary adenomas from craniopharyngioma, Rathke's cleft cyst (RCC), and other cystic sellar-suprasellar lesions. The data of 293 consecutive patients who underwent surgery for sellar-suprasellar lesions between July 2010 and December 2012 was retrospectively reviewed, and a total of 133 cystic cases were included in the present study. MR images and pathological features of all subjects were examined. Among the 133 cystic sellar-suprasellar masses, there were 78 cases of pituitary adenomas, 31 cases of craniopharyngioma, 21 cases of RCC, one case of epidermoid cyst and two cases of abscess. Fluid-fluid levels were identified n 43 cases (55.13%) of cystic pituitary adenomas, with a single fluid level in 23 cases, two fluid levels in 8 cases, and three levels or more in 12 cases. Two cases (6.45%) of craniopharyngioma, and one case (4.76%) of RCC presented single fluid level. No instances of fluid-fluid levels were observed in epidermoid cyst or abscess. Fluid-fluid levels were typically exhibited on axial T2-weighted images. The identification of fluid-fluid level in cysts provides useful diagnostic value in distinguishing pituitary adenoma from other sellar-suprasellar lesions. The findings of the present study suggest that a sellar-suprasellar mass with a fluid-fluid level inside the tumor is most likely a pituitary adenoma, particularly if multiple fluid levels are observed in the same tumor. The fluid-fluid level is typically clearly depicted on axial or sagittal MR images, suggesting subacute or chronic hemorrhage in pituitary adenomas.

Differentiation between Cystic Pituitary Adenomas and Rathke Cleft Cysts: A Diagnostic Model Using MRI

BACKGROUND AND PURPOSE

Cystic pituitary adenomas may mimic Rathke cleft cysts when there is no solid enhancing component found on MR imaging, and preoperative differentiation may enable a more appropriate selection of treatment strategies. We investigated the diagnostic potential of MR imaging features to differentiate cystic pituitary adenomas from Rathke cleft cysts and to develop a diagnostic model.

MATERIALS AND METHODS

This retrospective study included 54 patients with a cystic pituitary adenoma (40 women; mean age, 37.7 years) and 28 with a Rathke cleft cyst (18 women; mean age, 31.5 years) who underwent MR imaging followed by surgery. The following imaging features were assessed: the presence or absence of a fluid-fluid level, a hypointense rim on T2-weighted images, septation, an off-midline location, the presence or absence of an intracystic nodule, size change, and signal change. On the basis of the results of logistic regression analysis, a diagnostic tree model was developed to differentiate between cystic pituitary adenomas and Rathke cleft cysts. External validation was performed for an additional 16 patients with a cystic pituitary adenoma and 8 patients with a Rathke cleft cyst.

RESULTS

The presence of a fluid-fluid level, a hypointense rim on T2-weighted images, septation, and an off-midline location were more common with pituitary adenomas, whereas the presence of an intracystic nodule was more common with Rathke cleft cysts. Multiple logistic regression analysis showed that cystic pituitary adenomas and Rathke cleft cysts can be distinguished on the basis of the presence of a fluid-fluid level, septation, an off-midline location, and the presence of an intracystic nodule (P = .006, .032, .001, and .023, respectively). Among 24 patients in the external validation population, 22 were classified correctly on the basis of the diagnostic tree model used in this study.

CONCLUSIONS

A systematic approach using this diagnostic tree model can be helpful in distinguishing cystic pituitary adenomas from Rathke cleft cysts.

MR imaging findings in colloid cysts of the sellar region: comparison with colloid cysts of the third ventricle and Rathke's cleft cysts

RATIONALE AND OBJECTIVES

To identify magnetic resonance (MR) imaging characteristics allowing specific preoperative discrimination between colloid cysts (CCs) of the sellar region and third ventricle (CC3rdv) versus Rathke's cleft cysts (RCCs).

MATERIALS AND METHODS

MR imaging data of 38 patients with histologically proven CCs/CC3rdv and RCC underwent retrospective analysis with respect to signal intensity and heterogeneity on T1- and T2-weighted images, presence of the dot sign, enhancement, size, location, and accompanying infundibular stalk abnormalities.

RESULTS

Thirteen patients had CCs, 12 had CC3rdv, and 13 had RCCs. Signal intensity on T1-weighted images was partly or entirely hyperintense (n = 8), iso- or mixed iso/hypointense (n = 5) in CCs; hyperintense (n = 8), isointense, or mixed hypo/isointense (n = 3) in CC3rdv and hyperintense (n = 9); or mixed (n = 4) in RCCs. On T2-weighted images, signal intensity was hypointense (n = 12) or hyperintense (n = 1) in CCs, hypointense (n = 9) or hyperintense (n = 2) in CC3rdv, and hypointense (n = 5) or iso/hyperintense (n = 8) in RCCs. T2-weighted images were unavailable in two patients. Only one questionable enhancement was found in CCs, whereas an enhancing rim was consistently seen in RCCs. The dot sign was present in 7 CCs, 8 CC3rdv, and 4 RCCs. Mean cyst diameters were 12.6 mm for CCs and 14.5 mm for RCCs. RCCs showed more frequent and even solely suprasellar extent contrary to CCs.

CONCLUSION

Cyst wall enhancement was found in all RCCs but in none of the CCs, making this feature a reliable discriminator between the two. Complementary, suprasellar extension was more frequent in RCCs, whereas signal hypointensity on T2w was more common in colloid cysts.