有鉤骨に発生した孤立性骨囊腫の2例

Solitary Bone Cyst in the Hamate Bone. Report of 2 Cases

　稀な有鉤骨に発生した孤立性骨囊腫を2例経験したので報告する．症例は17歳の女性と37歳の女性で，それぞれ打撲を契機とした左手関節痛，誘因なく出現した右手関節痛で受診し，単純X線検査で骨透亮像を指摘され，有鉤骨の骨囊腫が判明した．骨囊腫は，17歳の症例ではMRIのT1強調像で低信号，T2強調像で高信号に描出され典型的所見であったが，37歳の症例ではT1，T2強調像ともに高信号に描出され，非典型的であった．2例ともに病的骨折の危険性が高いと考え，インフォームドコンセントを得て病巣掻爬術および人工骨移植術を行った．

　Two cases of solitary bone cysts in the hamate bone are reported. The first case was a 17-year-old girl complaining of left wrist pain after a traumatic sprain. The second case was a 37-year-old woman complaining of right wrist pain but with no history of trauma. X-ray films showed radiolucent masses in the hamate bone in both cases. MR images obtained in the first case showed findings typical of a solitary bone cyst, with a low-intensity lesion appearing on T1-weighted images and a high-intensity lesion appearing on T2-weighted images. Atypical findings were seen in the second case, with high-intensity lesions appearing on both T1-and T2-weighted images. We performed curettage and artificial bone grafting after obtaining informed consent in both cases, which were at high risk for developing pathological fractures during daily activities.