嚢胞内を移動する塊をもった症候性ラトケ嚢胞の1例

A Rathke's cleft cyst with a moving mass in the cyst

I．はじめに

　CT及びMRIの出現以来，ラトケ嚢胞の報告は多い．報告上，嚢胞内容物は多様であり，髄液様の無色透明の液体，ゼリー状，白濁した粘液，乳汁様，顆粒状，画像上二層性を示すものなど種々様々である^1,7）．しかし嚢胞内に腫瘤を認めたとの報告はきわめて少ない．渉猟しえた限りではKucharczykらが嚢胞壁に固着したdesquamated cellular debrisをwaxy noduleと命名し報告し^2），その後Sumidaらも同様の症例を報告している^4）のみである．

　今回われわれは，嚢胞内を移動するmassをもったラトケ嚢胞を経験したので，若干の文献的考察を加えて報告する．また本例は画像上，視床下部への圧迫所見がないにも関わらず視床下部性の下垂体機能低下症を呈していた．その機序についても考察を加えた．

We reported a case of Rathke's cleft cyst (RCC) with a moving mass in the cyst. A fifty-eight-year-old woman complaining of headache was admitted to our hospital. She suffered from hyponatremia, hypothala-mic hypopituitarism, but did not show any neurological deficits, nor visual field.nor visual acuity disturbance.

MRI revealed an intrasellar cyst including a mass shadow and the cyst did not compress the hypothala-mus. Interestingly, this mass moved gradually from the floor to the posterior wall of the sella turcica according to changes in position from standing to supine.

We operated to remove the cyst partially by trans-sphenoidal approach. Xanthochromic fluid flowed out from the cyst. In addition, a brownish globular mass, 6 mm in diameter, existed within the cyst without con-nection to the surrounding tissue. Pathological findings showed that the capsule consisted of cuboid epithelium and was partially stratified, which confirmed the dia-gnosis of Rathke's cleft cyst. However, the mass was homogenously stained with H.E., containing no cells, cellular debris, nor connective tissue. PAS stain was negative. Though we could not clarify the material in the cyst, this case is very rary one of Rathke's cleft cyst.

This case demonstrated the possibility of hypothala-mic hypopituitarism in spite of the cyst being almost lo-cated in the sella turcica. We surmise that a cyst near the stalk of the pituitary gland, even if it is not so large, might compress the portal vein, and thus the function of hypothalamus-pituitary axis.