Department of Radiology, Robert Jones and Agnes Hunt Orthopaedic Hospital NHS Foundation Trust, Oswestry, Shropshire, SY10 7AQ, UK.
John Radcliffe Hospital Oxford, Oxford, UK.
Skeletal Radiol. 2021 Apr;50(4):801-806. doi: 10.1007/s00256-020-03628-0. Epub 2020 Oct 1.
Fatty or part-fatty intraosseous lesions are occasionally encountered while imaging the skeletal system. A number of case reports have proposed involution of calcaneal bone cysts to intraosseous lipomas, but this has never been proven. This paper sets out to prove that simple bone cysts (SBCs) can involute to fatty lesions indistinguishable from intraosseous lipomas.
The pathology and PACS databases at 2 specialist orthopedic hospitals were retrospectively interrogated for all cases of intraosseous lipomas or SBCs with cross-sectional imaging follow-up for SBCs and precursor or follow-up imaging for intraosseous lipomas, in the time period from August 2007 to December 2016. For intraosseous lipoma cases, these were only included if change in imaging appearances was observed.
There was no case of change in the appearance in intraosseous lipomas. Six cases of SBC with cross-sectional imaging follow-up were identified in one participating hospital and none in the other. The 6 cases were comprised of 4 male and 2 female patients. Two were located in the proximal humerus, one in the proximal tibia, and 3 in the os calcis. All cases demonstrated filling in of the cystic lesion with fat from the periphery, in 2 cases complete filling in, and in 4 cases partial fatty conversion.
SBCs can heal with fatty conversion of the cystic cavity, with partly cystic remnants. It is proposed that at least part of the so-called intraosseous lipomas are healed simple bone cysts.
在骨骼系统成像过程中偶尔会遇到脂肪或部分脂肪性骨内病变。有许多病例报告提出跟骨骨囊肿向骨内脂肪瘤的退行性变，但这从未得到证实。本文旨在证明单纯性骨囊肿（SBC）可退行性变，形成与骨内脂肪瘤无法区分的脂肪病变。
回顾性检索了 2 家专业骨科医院的病理和 PACS 数据库，纳入了 2007 年 8 月至 2016 年 12 月期间具有 SBC 横断面影像学随访的所有骨内脂肪瘤或 SBC 病例，以及具有 SBC 前驱或后续影像学的所有骨内脂肪瘤病例。对于骨内脂肪瘤病例，仅纳入观察到影像学表现改变的病例。
在骨内脂肪瘤中没有发现外观改变的病例。在一家参与医院发现了 6 例具有横断面影像学随访的 SBC，而另一家医院则没有。这 6 例病例包括 4 名男性和 2 名女性患者。2 例位于肱骨近端，1 例位于胫骨近端，3 例位于跟骨。所有病例均显示囊性病变从周围填充脂肪，2 例完全填充，4 例部分脂肪转化。
SBC 可通过囊性腔的脂肪转化愈合，部分囊性残留。据推测，所谓的骨内脂肪瘤中至少有一部分是愈合的单纯性骨囊肿。
