ラトケ嚢胞の臨床病理学的検討：MRIにおける嚢胞壁のエンハンス効果と病理組織所見の関連について

Clinocopathological findings in symptomatic Rathke's cleft cyst:correlation between enhancement effects on MRI and histopathology of the cyst wall

I．はじめに

　MRIの進歩によりラトケ嚢胞が稀ならず見つかるようになって以来，種々の信号強度を呈する嚢胞内溶液については多くの検討がなされているが，嚢胞壁についての検討は少ない^6,8,15）．報告例の中にはGd-DTPAで嚢胞壁がエンハンスされたとの記載があるものの，神経放射線学的にも病理組織学的にもエンハンスの意味については検討されていない^2,11）．

　病理組織学的にみるとラトケ嚢胞の嚢胞壁は一層の円柱上皮から構成されているが，時にこれに連続して重層扁平上皮を有することも稀ではないと報告されている^5,16）．またラトケ嚢胞に下垂体腺腫を合併していたとの報告もある^14）．

We have studied MR images and the histopathology of eight patients with symptomatic Rathke's cleft cysts.Six cases showed visual disturbance and two showed galactorrhea. In five, the cyst fluid had low signal in-tensity on T1-weighted images and high intensity on T2-weighted images; in 2, the cyst fluid had high in-tensity on both T1 and T2-weighted images; in 1, the cyst fluid had high intensity on T1-weighted images and low intensity on T2-weighted images. Enhance-ment of the cyst wall by Gd-DTPA was able to be dis-tinguished in six cases: two patients showed no en-hancement, two showed thin enhancement and the re-maining two, thick enhancement. Fluid aspiration and total resection of the cyst wall was performed in all pa-tients (three cases by the transcranial approach and five by the transsphenoidal approach). Normal pituitary glands were found in all cases during the operations. Histopathologically, ciliated epithelium with goblet cells was recognized in three cases. Non-ciliated epithe- lium was recognized in the other five. Stratified squamous component was recognized in one case and secondary inflammation, in another. Normal pituitary tissue was recognized in five cases. Immunohistochemi-cally, ciliated and non-ciliated epithelium was succesful-ly stained for detecting antibody against epithelial membrane antigen and/or carcinoembryonic antigen. Two cases with no enhancement of the cyst wall by Gd-DTPA showed only ciliated epithelum. Two cases with thin enhancement of the cyst wall had single layer epithelium with normal pituitary tissue. Two cases with thick enhancement of the cyst wall showed single layer epithelium with its stratified squamous component or with secondary inflammation. A close relationship was suggested between the enhancement effect on MRI and histopathology of the cyst wall.