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CASE REPORT article

Front. Oncol.

Sec. Cancer Imaging and Image-directed Interventions

Volume 15 - 2025 | doi: 10.3389/fonc.2025.1596391

IgG4-Related Disease-Like Lesion Arising within a Well-Differentiated Liposarcoma/an Atypical lipomatous tumor: Two Cases Report

Provisionally accepted
Naoki OikeNaoki Oike1*Tomoaki TOrigoeTomoaki TOrigoe2Akira OgoseAkira Ogose1,3Takashi AriizumiTakashi Ariizumi1Tomohiro MiyazakiTomohiro Miyazaki1Yudai MurayamaYudai Murayama4Taku HommaTaku Homma2Hajime UmezuHajime Umezu1TAKUYA WATANABETAKUYA WATANABE2Hiroyuki KawashimaHiroyuki Kawashima1
  • 1Niigata University, Niigata, Japan
  • 2International Medical Center, Saitama Medical University, Saitama City, Japan
  • 3Uonuma Kikan Hospital, Minamiuonuma, Niigata, Japan
  • 4Tochigi Cancer Center, Utsunomiya, Tochigi, Japan

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Introduction: Well-differentiated liposarcoma (WDLPS) is a locally aggressive soft tissue sarcoma characterized by the amplification of MDM2 and/or CDK4. IgG4-related disease (IgG4-RD) is a rare fibroinflammatory disease characterized by elevated serum IgG4 levels and histologically fibrous tissues with IgG4-positive immune cell infiltration. Although IgG4-RD often mimics other diseases, including malignant neoplasms, the association between IgG4-RD and WDLPS has not been fully elucidated. Here, we present two cases of IgG4-RD occurring within WDLPS. Case presentation: A 56-year-old man presented with a left retroperitoneal mass, and a 64year-old woman presented with a non-tender mass in her right thigh. Magnetic resonance imaging revealed that the tumors were composed of adipose and non-adipose areas with homogeneous enhancement. A biopsy revealed that the tumor consisted of adipose cells of various sizes and fibrous tissue with IgG4-positive cell infiltration. MDM2 amplification was detected using fluorescence in situ hybridization in both the adipose and fibrous areas. In addition, serum IgG4 levels were elevated in both patients, and IgG4-RD within the WDLPS were diagnosed. Wide resection was performed as radical treatment. After resection, the serum IgG4 level decreased to normal. No recurrence or metastasis has been observed for >19 months. Conclusion: Our cases highlight the importance of careful biopsy for the accurate diagnosis of patients with IgG4-RD within WDLPS. Moreover, although the main treatment for IgG4-RD is systemic corticosteroids, IgG4-RD within WDLPS should be treated with surgical resection.

Keywords: Inflammatory, IgG4, IgG-4 related disease, Soft Tissue Sarcoma, Well differentiated liposarcoma, Murine double minute 2, case report

Received: 19 Mar 2025; Accepted: 11 Aug 2025.

Copyright: © 2025 Oike, TOrigoe, Ogose, Ariizumi, Miyazaki, Murayama, Homma, Umezu, WATANABE and Kawashima. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Naoki Oike, Niigata University, Niigata, Japan

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