Rathke cleft cyst of the sphenoid bone and nasopharynx

Abstract

1095 Manuscript received May 31, 2004; accepted in final form August 30, 2005. Address reprint requests to: Karim Ben Hamouda, M.D., Service de Neurochirurgie, Institut National de Neurologie, La Rabta, 1007, Tunis, Tunisia. email: kbenhamouda@lycos.com. We report an exceptional case of a sphenoidal and nasopharyngeal Rathke cleft cyst (RCC). In a literature review, we found that this cyst had never been described in this region. This 41-year-old man presented in August 2002 with progressive headaches, ptosis, and diplopia. In November 2002, he experienced a spontaneous episode of rhinorrhea and a complete subsequent resolution of the symptoms. In February 2003, the frontal headaches relapsed, associated this time with a progressive decrease in left-sided visual acuity. On clinical examination in April 2003, the patient had an isolated loss of visual acuity (1/10) in the left eye. Endocrinological assessment demonstrated normal results. Computerized tomography scanning revealed that the sphenoid region had been destroyed by a large noncalcified low-density cystic lesion. Magnetic resonance (MR) imaging demonstrated a cystic sphenoidal extradural lesion that was isointense on T1-weighted sequences and peripheral enhancement after Gd enhancement (Fig. 1 left); hyperintensity was observed on T2-weighted images (Fig. 1 right). The maximal diameter of the lesion was 4 cm. There was also a smaller contiguous cyst on the posterior wall of the nasopharynx. A transrhinoseptal approach was used. The wall of the sphenoid sinus was paper thin; a motor oil–like fluid escaped. The cyst widely communicated with the nasal fossa, and its wall was partially extirpated. The dura covering the sellar floor was unperforated. Pathological examination showed a columnar ciliated epithelium (Fig. 2) consistent with an RCC. The postoperative course was uneventful; all symptoms resolved and no neurological symptoms developed. Imaging performed 1 week after surgery revealed partial evacuation of the cyst, with reappearance of the pituitary gland and a morphologically normal pituitary stalk. We also observed the persistence of a nasopharyngeal cyst under the sphenoidal lesion. One year later imaging revealed the disappearance of the sphenoidal cyst and the persistence of the lesion located on the posterior wall of the nasopharynx (Fig. 3). The sphenoidal, infrasellar origin of this RCC is supported by the absence of a suprasellar extension and by its entirely extradural location. Remnants of the craniopharyngeal canal can originate in a spectrum of cystic lesions, from simple RCCs to complex craniopharyngiomas.1 According to Erdheim’s theory,2 a craniopharyngioma can arise from every part of the craniopharyngeal canal. This may be also true for an RCC. In our case, it seems that the cyst derived from the canal enclosed in the cranial base bones, in contact with the walls of the pharynx. Computerized tomography and MR imaging features of RCC are not specific and are seen in more common lesions in this area such as craniopharyngiomas and mucoceles. The preoperative diagnosis of RCC is theoretically important because it may limit the operative management to biopsy sampling of the cyst wall and drainage of the contents via the transsphenoidal route.1 Voelker and colleagues3 concluded in a review of 155 cases that the transsphenoidal approach is optimal choice for sellar and suprasellar RCC and that partial excision and drainage of these cysts are the recommended treatments. In this case the sphenoid cyst disappeared after a partial excision of its walls.