Department of Radiology and Cancer Biology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8588, Japan.
Department of Radioisotope Medicine, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8588, Japan.
Skeletal Radiol. 2021 Jan;50(1):249-254. doi: 10.1007/s00256-020-03521-w. Epub 2020 Jun 25.
Myositis ossificans (MO) is a benign soft-tissue lesion characterized by the heterotopic formation of the bone in skeletal muscles, usually due to trauma. MO is occasionally difficult to diagnose because of its clinical and radiological similarities with malignancy. We report a case of traumatic MO (TMO) in the masseter and brachial muscles of a 37-year-old man who presented with painless swelling in the left cheek and severe trismus. Due to the absence of a traumatic history at the first consultation and identification of a tumorous lesion in the left masseter muscle by magnetic resonance imaging (MRI), the lesion was suspected to be a malignant tumor. Subsequently, 18F-fluorodeoxyglucose positron-emission tomography/computed tomography (FDG-PET/CT) showed multiple regions of high FDG uptake across the whole body, suggestive of multiple metastases or other systemic diseases. However, intramuscular calcifications were also observed in the left masseter and brachial muscles, overlapping the areas with high FDG uptake. Moreover, multiple fractures were seen in the rib and lumbar spine, also overlapping the areas with high FDG uptake. Based on these imaging findings, along with a history of jet-ski trauma, TMO was suspected. The left cheek mass was surgically excised and histologically diagnosed as TMO. In this case report, FDG-PET/CT could detect multiple TMOs across the whole body. To the best of our knowledge, cases of multiple TMOs located far apart in different muscles are rare, and this may be the first report.
骨化性肌炎（MO）是一种良性软组织病变，其特征是骨骼肌肉中异位形成骨，通常由创伤引起。MO 偶尔难以诊断，因为其临床表现和影像学与恶性肿瘤相似。我们报告了一例 37 岁男性的创伤性 MO（TMO），其表现为左脸颊无痛性肿胀和严重的牙关紧闭。由于初次就诊时无创伤史，且磁共振成像（MRI）显示左咬肌内存在肿瘤性病变，因此怀疑该病变为恶性肿瘤。随后，18F-氟脱氧葡萄糖正电子发射断层扫描/计算机断层扫描（FDG-PET/CT）显示全身多个区域 FDG 摄取增高，提示存在多发转移或其他全身性疾病。然而，左咬肌和肱二头肌也观察到肌内钙化，与 FDG 摄取增高的区域重叠。此外，肋骨和腰椎也可见多处骨折，与 FDG 摄取增高的区域重叠。基于这些影像学发现，结合喷气滑水创伤史，怀疑为 TMO。左脸颊肿块被手术切除，并组织学诊断为 TMO。在本病例报告中，FDG-PET/CT 可检测全身多处 TMO。据我们所知，位于不同肌肉且相距较远的多处 TMO 非常罕见，这可能是首例报告。
