Ando Yuki, Ito Risako, Matsuo Hiromi, Baba Kyoko
Plastic Surgery, Kitasato University Medical Center, Kitamoto, JPN.
Department of Plastic and Aesthetic Surgery, Kitasato University School of Medicine, Sagamihara Kanagawa, JPN.
Cureus. 2025 Feb 6;17(2):e78642. doi: 10.7759/cureus.78642. eCollection 2025 Feb.
We report a rare case of a smooth muscle tumor of uncertain malignant potential arising in the inguinal soft tissue, requiring differential diagnosis from metastatic lymphadenopathy. The patient was a 74-year-old male. On the initial examination, a painless, elastic-firm mass measuring approximately 25 × 15 mm was palpated slightly cephalad and medial to the left inguinal region. The mass was non-adherent to the overlying skin or underlying tissue. Based on preoperative imaging findings, metastatic lymphadenopathy was considered likely. However, further evaluation by the urology department found no definitive evidence of prostate cancer, and cystoscopy ruled out bladder cancer. Under local anesthesia, the tumor was excised and subjected to histopathological analysis. Histopathological examination with hematoxylin and eosin staining revealed a fibrous capsule surrounding the tumor and spindle-shaped cells with atypical nuclei arranged in loose bundles and fascicles within the tumor. Immunohistochemical staining showed positive results for desmin and alpha smooth muscle actin, while S-100 protein and CD34 were negative. B cell lymphoma 2 and Signal transducer and activator of transcription 6 were weakly positive, while β-catenin was negative. Thus, the histopathological findings were assessed, and the tumor was classified as a smooth muscle tumor of uncertain malignant potential. The patient's postoperative course was uneventful, with no evidence of recurrence at two years post-surgery. Smooth muscle tumor of uncertain malignant potential is defined as a "soft tissue tumor of uncertain malignant potential that does not meet the diagnostic criteria for conventional leiomyoma, its various subtypes, or leiomyosarcoma." To our knowledge, this case represents an exceedingly rare occurrence of smooth muscle tumor of uncertain malignant potential in the field of plastic and orthopedic surgery.
我们报告了一例罕见的发生于腹股沟软组织的恶性潜能不确定的平滑肌瘤病例，需要与转移性淋巴结病进行鉴别诊断。患者为一名74岁男性。初次检查时，在左腹股沟区稍上方和内侧可触及一个无痛性、质地坚韧有弹性的肿块，大小约为25×15mm。该肿块与上方皮肤或下方组织无粘连。根据术前影像学检查结果，考虑可能为转移性淋巴结病。然而，泌尿外科进一步评估未发现前列腺癌的确切证据，膀胱镜检查排除了膀胱癌。在局部麻醉下，切除肿瘤并进行组织病理学分析。苏木精-伊红染色的组织病理学检查显示肿瘤周围有纤维性包膜，肿瘤内有梭形细胞，核异型，呈松散束状和 fascicles排列。免疫组织化学染色显示结蛋白和α平滑肌肌动蛋白呈阳性，而S-100蛋白和CD34呈阴性。B细胞淋巴瘤2和信号转导及转录激活因子6弱阳性，而β-连环蛋白阴性。因此，对组织病理学结果进行评估，该肿瘤被分类为恶性潜能不确定的平滑肌瘤。患者术后恢复顺利，术后两年无复发迹象。恶性潜能不确定的平滑肌瘤被定义为“不符合传统平滑肌瘤、其各种亚型或平滑肌肉瘤诊断标准的恶性潜能不确定的软组织肿瘤”。据我们所知，该病例代表了整形和矫形外科领域中极为罕见的恶性潜能不确定的平滑肌瘤发生情况。
