Kawasaki Tomonori, Ichikawa Jiro, Onohara Kojiro, Kanno Satoshi, Wako Masanori, Taniguchi Naofumi, Ochiai Satoshi, Torigoe Tomoaki, Yazawa Yasuo
Department of Pathology, Saitama Medical University International Medical Centre, Saitama, Japan.
Department of Orthopaedic Surgery, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan.
Skeletal Radiol. 2025 May;54(5):1147-1151. doi: 10.1007/s00256-024-04768-3. Epub 2024 Jul 31.
IgG4-related disease is a rare fibroinflammatory disorder characterized by the infiltration of IgG4-rich plasma cells. Herein, we report a case of IgG4-related disease of the subcutaneous tissue with atypical MRI findings and difficulties in the histopathological examination using needle biopsy. Based on the clinical presentation and MRI findings, the patient was diagnosed with a benign myxoid or cystic tumor. Additionally, histopathological findings from a needle biopsy suggested a myxoma. Therefore, the correct diagnosis of IgG4-related disease was not made preoperatively. The resected specimens confirmed IgG4-related disease with an IgG4/IgG ratio > 80%. Previous reports have shown that the MRI findings of IgG4-related disease mimic both malignancy and inflammation; surprisingly, the features of subcutaneous IgG-related disease, including tail sign, unclear border, and heterogeneous enhancement, were similar to those found in sarcoma. Therefore, histopathological findings are needed for a correct diagnosis. Furthermore, careful examination is essential because the neoplasm and inflammation may overlap with IgG4-related disease, and needle biopsy is not fully reflective of the tumor. As is highlighted in the present case, IgG4-related disease is often misdiagnosed; therefore, clinicians should adequately recognize that even if the histopathological findings in biopsy were consistent with those observed in the MRI, misdiagnosis may occur.
IgG4相关性疾病是一种罕见的纤维炎性疾病，其特征为富含IgG4的浆细胞浸润。在此，我们报告一例皮下组织IgG4相关性疾病，该病例具有非典型的MRI表现，且针吸活检组织病理学检查存在困难。基于临床表现和MRI表现，该患者被诊断为良性黏液样或囊性肿瘤。此外，针吸活检的组织病理学结果提示为黏液瘤。因此，术前未做出IgG4相关性疾病的正确诊断。切除标本证实为IgG4相关性疾病，IgG4/IgG比值>80%。既往报道显示，IgG4相关性疾病的MRI表现可模仿恶性肿瘤和炎症；令人惊讶的是，皮下IgG相关性疾病的特征，包括尾征、边界不清和不均匀强化，与肉瘤相似。因此，正确诊断需要组织病理学结果。此外，仔细检查至关重要，因为肿瘤和炎症可能与IgG4相关性疾病重叠，且针吸活检不能完全反映肿瘤情况。正如本病例所强调的，IgG4相关性疾病常被误诊；因此，临床医生应充分认识到，即使活检的组织病理学结果与MRI所见一致，仍可能发生误诊。
