Elsevier

World Neurosurgery

Volume 98, February 2017, Pages 882.e15-882.e20
World Neurosurgery

Case Report
Rathke Cleft Cyst with Entirely Ossified Cyst Wall and Partially Solid Cyst Content: A Case Report and Literature Review

https://doi.org/10.1016/j.wneu.2016.10.052Get rights and content

Background

In Rathke cleft cysts (RCCs), inflammation by the cyst contents infrequently spreads to the surrounding structures. Calcification, which is regarded as a result of chronic inflammation of the cyst wall, can rarely be found in RCCs. Moreover, ossification is extremely rare.

Case Description

A 60-year-old woman experienced headaches, fatigue, and weight loss owing to pan-hypopituitarism. Magnetic resonance imaging revealed a mass lesion in the sellar region, which was composed of two different parts, with hypointensity anteriorly and hyperintensity posteriorly on T1-weighted image, and the rim with significant hypointensity entirely on T2-weighted image. During the transsphenoidal surgery, the cyst wall was so rigid that it was difficult to cut and remove it. The cyst contained mucinous fluid with both old and new hemorrhages, and a yellowish, elastic hard, solid nodule. Postoperative histologic diagnosis was RCC with unusual lymphocyte infiltration, massive granulation, and mature bone formation. Six months later, the fluid in the cyst reaccumulated, and the patient complained of headaches. Removal of the entire cyst wall and the aspiration of the cyst content were performed to collapse the cyst cavity and, consequently, to prevent further recurrence. Postoperatively, panhypopituitarism was unchanged and the symptoms were treated with hormonal replacement. The cyst has not recurred for 2 years after the second surgery.

Conclusions

Persistent, long-term inflammation induced by the RCC content, mucin-containing fluid, and several phases of hemorrhage presumably promoted the formation of mature bone on the cyst wall and of the elastically solid nodule within the cyst.

Introduction

Rathke cleft cysts (RCCs) are non-neoplastic, epithelial-lined cysts located in the sellar and suprasellar regions, which are known to be derived from the remnants of the Rathke pouch at 3–4 weeks' gestation.1, 2, 3 RCCs are diagnosed with histologic verification of a single layer of cuboidal or columnar epithelium, including cilia and goblet cells, which secret mucus into the cyst cavity.2, 4 RCCs are usually asymptomatic and can be found in 13%–22% of unselected autopsy studies.1, 2, 5 Inflammation spread by the cyst contents and the effects of the cyst compressing on the surrounding structures infrequently induce headaches, endocrinologic insufficiency, and visual function disturbance.6, 7, 8

Although calcification of the cyst wall in RCC is rare, ossification occurs even less frequently, as only four cases have been reported.4, 9, 10, 11 Because calcification is commonly found in craniopharyngioma, its presence plays an important role in distinguishing the 2 disorders.12, 13 Although, it is believed that calcification can arise from chronic inflammation of the wall, the detailed mechanism of ossification in RCC remains unknown. In this case, the developmental mechanism of an extremely rare case of ossified RCC was explored with an immunohistochemistry (IHC) study.

Section snippets

Case Description

A 60-year-old woman complaining of headaches, fatigue, and weight loss consulted the local hospital in May 2013. Computed tomography showed a round cyst in the sellar region and calcification on the cyst wall (Figure 1A). Magnetic resonance imaging (MRI) revealed an oval mass in the sellar region with suprasellar extension. The mass had two different parts of anterior hypointensity with heterogeneous contrast enhancement and of homogeneous posterior hyperintensity on T1-weighted imaging (

Discussion

Although ossification of the sellar lesion is usually found in craniopharyngioma, it is extremely rare in RCC and, to our knowledge, only 4 cases have been reported.4, 9, 10, 11 In craniopharyngioma, the ossification is presumed to be caused by metaplasia owing to chronic inflammation. Sato and Kubota13 proposed the mechanism of ossification based on a study using light and electron microscopy. They observed that keratinized cell masses in craniopharyngioma sometimes came into direct contact

Conclusion

Long-term of chronic inflammation induced by the RCC content could promote mature bone formation, an elastically solid nodule, and old and new phases of hemorrhage possibly from granulation tissue. This metaplastic ossification of the wall strongly suggested unusual, extreme, and complex process of persistent inflammation.

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    Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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