Department of Orthopedic surgery, Hôpital Maisonneuve-Rosemont, Université de Montréal, Montréal, Québec, Canada.
Department of Orthopedic surgery, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
Skeletal Radiol. 2020 Oct;49(10):1499-1503. doi: 10.1007/s00256-020-03464-2. Epub 2020 May 20.
Aneurysmal bone cyst (ABC) is a benign locally destructive lesion that usually developed in the bone cavity of bones, less commonly on the surface of cortical bones and very rarely develop outside the bone. There are only 35 reports of extraskeletal aneurysmal bone cyst (ESABC) in the English literature. We report a case of a 12-year-old female with no history of trauma who presented with knee pain. Imaging studies revealed an infrapatellar mass that was fast to calcify during a period of 3 months. MRI showed high T2 center, low T1 signal, and heterogenic enhancement with a rim of low intensity consistent with calcified boarders surrounded by severe soft tissue edema. The lesion was surgically excised, and a histological examination revealed an aneurysmal bone cyst possibly arising within myositis ossificans or heterotopic ossification. In her last follow-up 1.5 years after the surgical excision, the patient was symptom free and without signs of recurrence. To the best of our knowledge, this is the first reported case of an intra-articular ESABC located in the knee.
骨巨细胞瘤（ABC）是一种良性局部破坏性病变，通常发生在骨腔的骨中，较少发生在皮质骨表面，非常罕见于骨外。英文文献中仅有 35 例骨外骨巨细胞瘤（ESABC）的报道。我们报告了一例 12 岁女性患者，无外伤史，表现为膝关节疼痛。影像学检查显示髌下肿块，在 3 个月内快速钙化。MRI 显示 T2 中心高信号，T1 信号低，不均匀强化，伴有低信号环，提示边界钙化，周围有严重的软组织水肿。病变通过手术切除，组织学检查显示可能起源于骨化性肌炎或异位骨化的骨巨细胞瘤。在手术切除后 1.5 年的最后一次随访中，患者无症状，无复发迹象。据我们所知，这是首例报道的位于膝关节的关节内 ESABC。
