Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
Department of Radiology, C-2-S, Leiden University Medical Center, PO Box 9600, 2300RC, Leiden, The Netherlands.
Skeletal Radiol. 2019 Jul;48(7):1059-1067. doi: 10.1007/s00256-018-3135-x. Epub 2019 Jan 2.
Aneurysmal bone cysts (ABC) rarely present in soft tissue locations (STABC). The 30 cases of STABC reported in the English literature were reviewed. Six new cases retrieved from the files of the Netherlands Committee on Bone Tumors were compared to the six cases described in the radiological literature.
Imaging studies and histopathology of six new STABC cases were reviewed. Follow-up was recorded with respect to local recurrence. FISH for USP6 rearrangement and/or anchored multiplex PCR-based targeted NGS using Archer FusionPlex Sarcoma Panel were attempted.
On imaging, the six STABC cases presented as a solid or multicystic intramuscular soft tissue mass, usually with thin peripheral mineralized bone shell. On MRI, perilesional edema was visualized in nearly all cases. Fluid-fluid levels were observed in one case. All lesions had the distinct histologic features of STABC. In three cases suitable for NGS, the diagnosis of STABC was confirmed by a COL1A1-USP6 fusion gene. In one additional case, USP6 gene rearrangement was detected by FISH. After marginal excision, none of the six STABC recurred after a mean follow-up period of 50 months (range, 39-187 months).
On imaging, it can be difficult to discriminate between STABC and myositis ossificans. The presence of a thin bony shell and fluid-fluid levels can be helpful in discriminating these two entities. STABC is readily diagnosed after histopathologic examination of the resection specimen. STABC belongs to the spectrum of tumors with USP6 rearrangements, which includes ABC, myositis ossificans, and nodular fasciitis.
动脉瘤样骨囊肿（ABC）很少发生于软组织部位（STABC）。本文回顾了英文文献中报道的 30 例 STABC，并将从荷兰骨肿瘤委员会档案中检索到的 6 例新病例与放射学文献中描述的 6 例病例进行比较。
对 6 例新的 STABC 病例的影像学研究和组织病理学进行了回顾。记录了局部复发情况。尝试进行 USP6 重排的 FISH 和/或基于锚定多重 PCR 的靶向 NGS（使用 Archer FusionPlex Sarcoma Panel）。
在影像学上，6 例 STABC 表现为实性或多囊性肌内软组织肿块，通常有薄的外周矿化骨壳。在 MRI 上，几乎所有病例均可见周围水肿。一例可见液-液平面。所有病变均具有 STABC 的明显组织学特征。在 3 例适合 NGS 的病例中，通过 COL1A1-USP6 融合基因诊断为 STABC。在另外 1 例中，通过 FISH 检测到 USP6 基因重排。在边缘切除后，6 例 STABC 在平均 50 个月（范围，39-187 个月）的随访期内均无复发。
在影像学上，STABC 与骨化性肌炎之间可能难以区分。薄的骨壳和液-液平面的存在有助于区分这两种病变。切除标本的组织病理学检查后，STABC 很容易诊断。STABC 属于具有 USP6 重排的肿瘤谱，包括 ABC、骨化性肌炎和结节性筋膜炎。
