症候性ラトケ嚢胞の臨床検討

Clinical Study of Symptomatic Rathke Cleft Cyst

I．はじめに

　トルコ鞍内に生じる上皮性嚢胞はラトケ嚢胞（Rathke cleft cyst，以下RCCと略）と呼ばれ，胎生期におけるRathke pouchの遺残より発生すると考えられている。そして正常人でも剖検時11-22％の頻度で認められるとの報告がある^15,16,18）．一方，その嚢胞の増大により下垂体や視交叉を圧迫し種々の臨床症状を呈する症候性RCCは稀とされていたが近年，CTスキャンやMRの普及に伴いその報告例は増加し^9,12,19），決して稀な疾患とはいえない．しかしながら，個々の症例報告が散見されるのみで，多数例の長期にわたる経過を追跡した報告は少ない．

　今回，われわれは過去10年間に1施設で経験し，手術により病理組織診断の確立された症候性RCC 12症例につきCTならびにMRI所見，臨床症状，手術アプローチ，そして再発例につき検討を加えて報告する．

The clinical, radiographic findings in 12 patients with symptomatic Rathke cleft cysts (RCC) are pre-sented. The mean age of these patients was 52 years, and 9 of the patients were female. Visual disturbancewas the most common symptom, followed by headache. Magnetic resonance images (MRIs) were re-viewed in 11 cases. In two cases, the cyst fluid had low signal intensity on Tl-weighted images and highintensity on T2-weighted images. In eight cases the cyst fluid had iso-to-high intensity on both Ti and T2-weighted images. On dynamic MRI study using Gd-DTPA, normal anterior pituitary gland was seen su-perior to the RCC in 4 cases, anterior in 4, and inferior in 2 cases. In accordance with the MRI findings,transcranial approach was chosen in 4 cases and the transsphenoidal route was used in eight cases. Mostsymptoms and signs improved or resolved following surgery with the exception of those cases with a long-standing history of hypopituitarism. We experienced two cases of recurrence at 7 months, and 65 monthsrespectively requiring a second operation, and the mean follow-up period for all cases was 78 months. Dif-ferential diagnosis between RCC and craniopharyngioma should be carefully made in the recurrent casesby surgical specimens of the cyst wall.

Partial resection of the cyst wall and drainage of the contents via the transsphenoiclal route is a safe andeffective procedure in the majority of cases, but the transcranial approach is the treatment of choice incases in which the cyst is entirely located in the suprasellar region.