大腿骨近位部に発生したliposclerosing myxofibrous tumorの1例

Liposclerosing Myxofibrous Tumor of the Proximal Femur. Case Report

　大腿骨近位部に発生した稀なliposclerosing myxofibrous tumor(以下LSMFT)の1例を経験した．症例は63歳の女性で右股関節痛を主訴に当院を受診した．単純X線像で腫瘍は右大腿骨近位部の辺縁硬化を伴う溶骨性病変で内部に骨化がみられた．病的骨折が危惧されたため骨腫瘍掻爬および人工骨充塡術を施行した．掻爬検体の組織像で線維性骨異形成様の幼若骨を伴う線維増生，モザイク状のセメントラインを持つ骨形成など多彩な像を呈しており，LSMFTと診断した．LSMFTは良性の線維性骨性病変であるが10～16％の症例で悪性転化を生じるため，切除検体の組織像の詳細な検索や長期に及ぶ経過観察が必要である．

　Liposclerosing myxofibrous tumor (LSMFT) is a benign fibro-osseous lesion characterized by a complex mixture of histological elements, including lipoma, fibroxanthoma, myxofibroma, fibrous dysplasia-like features, cyst formation, fat necrosis, and ischemic ossification.　It is relatively new entity and appears to be rare.　We report a case of LSMFT of the proximal femur.　A 63-year-old woman presented with a 2-week history of right hip pain.　Plain radiographs revealed a clearly defined osteolytic lesion with sclerotic rim in the intertrochanteric region of the right proximal femur, and calcification was seen within the lesion.　We performed curettage and made a diagnosis of LSMFT based on the presence of typical histological features.　Despite its histological complexity, LSMFT has a relatively characteristic radiological appearance and skeletal distribution.　According to the literature, the prevalence of malignant transformation is high (10－16%).　LSMFT patients should be carefully monitored for malignant transformation, and a long follow-up period is required.