思春期早発症をきたしたくも膜嚢胞の1手術例

Suprasellar Arachnoid Cyst Associated with Precocious Puberty: Report of an operated case and review of the literature

I．はじめに

　真性（中枢性）思春期早発症の原因の多くは特発性であるが，視床下部過誤腫などのような器質的疾患の存在も明らかとなっている^14）．今回，われわれは鞍上部から後頭蓋窩に拡がるくも膜下嚢胞が原因と考えられる思春期早発症のまれな1女児例を経験した．嚢胞腹腔短絡術を行ったところ臨床症状は改善した．くも膜嚢胞による思春期早発症の発生機序と治療法について若干の文献的考察を加えて報告する．

　The pathogenesis remains unknown in the majority ofpatients with precocious puberty, and yet infrequently such causative cerebral lesions as hypothalamic hamartomas are associated with sexual precocity. We reported a rare case of suprasellar arachnoid cyst in an infant presenting with precocious puberty, which eventually disappeared after a cyst-peritoneal shunt. It was believed that the mass effect of the arachnoid cyst upon the hypothalamus was, at least in part, responsible for development of precocious puberty. The role of surgical decompression of the cyst was also discussed.

　A one-year-old girl was admitted to the hospital for evaluation of genital bleeding which had persisted on and off for two months. The height, 80cm, and the weight, I2.4kg, exceeded by far the two standard deviations from the mean level of the normal population. In addition she had the development of breast tissue as classified Tanner's Stage II, and both pubic and axillary hair. The bone age by skeletal survey of the hand was rated as 3 years. Endocrinological examination showed that serum levels of lutenizing hormone(LH), folliclestimulating hormone(FSH) and estradiol had increased for her age, to levels equivalent to those for females at puberty. An LHRH test revealed an excessive LH reaction. There were no definite neurological deficits. CT and MRI demonstrated the presence of a large arachnoicl cyst involving the suprasellar region as well as the right middle and posterior fossa. After the patient underwent a cyst-peritoneal shunt, the cyst decreased in size and such symptoms as genital bleeding and breast growth disappeared. Serum levels of her LH and FSH also significantly decreased. Sixteen months after the surgery, however, symptoms clue to increased intracranial pressure developed and the regrowth of the cyst was comfirmed on CT. Genital bleeding also recurred. The cyst-peritoneal shunt was then revised by exchanging the peritoneal catheter of medium pressure for that of low pressure. Postoperatively genital bleeding disappeared again, which seemed to well correspond to a marked reduction in size of the cyst on CT scan.