髄膜腫と鑑別困難であったErdheim-Chester diseaseの1例

A Case of Erdheim-Chester Disease that was Difficult to Differentiate from Meningioma

Ⅰ．はじめに

　Erdheim-Chester disease（ECD）は，非ランゲルハンス細胞性組織球症の中でも稀な疾患である．1972年に提唱され，2004年まで世界で100例にも満たない報告数であった．しかし近年，報告数の増加とともに，2013年の米国サンディエゴでのシンポジウム以来，世界的に研究が進められBRAF^V600E遺伝子変異との関係も明らかになっている．

　今回，大脳鎌およびテント部，鞍上部に多発性に発生したECDの手術症例を経験したので，文献的考察を加えて報告する．

　OBJECTIVE：Erdheim-Chester disease（ECD）is a rare type of non-Langerhans histiocytosis. We report a surgical case of ECD with multiple lesions at the falx cerebri, tentorium cerebelli, and in the suprasellar region, with a literature review.

　CASE REPORT：A 70-year-old woman presented with frequent falling and difficulty in standing. Her past medical history revealed ovarian cystectomy, transient thrombocytopenia, hypertension, left lower leg pain, and overactive bladder. Her head CT and MRI findings revealed well-defined mass lesions, suspected of meningioma, at the falx cerebri and tentorium cerebelli. Craniotomy and near total resection of the tumor at the falx cerebri was performed, leaving a hard portion of the tumor on the right falx. Intraoperative findings showed a solid and hard tumor, which was extremely difficult to decompress. Although the histopathological diagnosis was originally a metaplastic meningioma, considering her complaints of lower leg pain, we suspected ECD and performed a right tibial biopsy. The right tibial biopsy revealed ECD. Twenty-two months after the operation, the patient exhibited a marked enlargement of the tentorium lesion and a new lesion in the suprasellar region. Resection of the tentorial lesion was performed. The second intraoperative findings were similar to those of the first. The histopathological diagnosis of the tentorial lesion was ECD. After the surgeries, steroid therapy and radiation therapy were performed, but only with temporary improvement.

　CONCLUSION：ECD is a rare disease；therefore, accumulation of clinical data to establish its treatment is necessary.