LGMS was first proposed by Vasude et al. in 1978, which was confirmed by Mentzel et al. in 1998, and finally confirmed by Montgomery et al. as a unique entity [8]. Due to the lack of unified diagnostic criteria, LGMS was also called myofibrosarcoma, myofibroblast sarcoma, myofibroblast-rich fibrosarcoma, and leiomyosarcoma in the past [13]. LGMS was first classified as a distinct entity in the 2002 WHO Classification of Pathology and Genetics of Tumors of Soft Tissue and Bone. In subsequent editions, it is still referred to as LGMS and is classified as part of the fibroblastic/myofibroblastic tumor category. According to literature statistics, LGMS occurs frequently in the head, neck and extremities, and is prone to local recurrence, and the oral cavity (especially the tongue) is the most common affected area [7,17]. So far, LGMS is uncommon in clinical cases, and few cases have been reported. Mainly due to the lack of unique biological characteristics of LGMS and the lack of in-depth imaging studies, the pathological identification of myofibroblasts is mainly diagnosed by light microscopy and immunohistochemistry [8,10]. Zhang Shikun [3] et al. mentioned in the literature that in vivo molecular imaging had unique advantages in diagnosing tumors. It can obtain higher spatial resolution at a lower cost and can detect highly sensitive, high-resolution imaging in deep tissues. Therefore, it is speculated that the new molecular imaging technology may be helpful for the diagnosis and prognosis of LGMS. LGMS in most parts is ignored in the early stage because of the painless mass, or misdiagnosed as other diseases with similar symptoms or images [11,14], most often misdiagnosed as inflammatory myofibroblastic tumor (IMT). Both LGMS and IMT belong to myofibroblastic tumors, which are similar in tissue morphology and MR appearance, and are easily confused [3,13]. However, there are differences in growth characteristics, morphology, and immunohistochemistry between the two diseases. This is similar to the analogous report in the previous article. The patient had no specific symptoms and abnormal physical examination in the outpatient physical examination, and the palpation of the tumor was similar to that of a conventional lipoma. Ultrasound and MRI examination reports indicated that abnormal booth lesions were admitted to hospital for treatment. During the operation, the shape of the tumor was obviously different from that of conventional lipoma, and the general shape of the specimen did not have typical characteristics. Mana [16] found that LGMS were loose, branched fragments of spindle-shaped tumor cells with unclear cell boundaries during the needle aspiration cytology detection of LGMS. Nuclei vary in shape from ovate to fusiform, including angular and bare nuclei. Nuclei are mildly to moderately pleomorphic, with occasional nucleoli. Ni C [12] et al. concluded in the literature that plasma cell inflammatory cell infiltration is obvious in IMT, but rare in LGMS; LGMS has a more uniform histological pattern, with more mitotic figures and nuclear atypia; in Cytokeratin and ALK are present in some subpopulations of IMTs but absent in LGMS. Combining several factors can help to make a differential diagnosis between the two diseases.

For the current treatment of LGMS, a unified plan has not been reached in the existing cases. The current optimal treatment plan for LGMS is still controversial, and there are large differences in efficacy. However, surgical treatment is still the main method, and a small number of patients use surgery plus radiotherapy and chemotherapy [6,10]. Long Peng [6] et al. reported a case of pancreatic LGMS after two cycles of adjuvant chemotherapy for 5 years without tumor recurrence; Niu Rong [15] et al. reported a case of gastric cardia LGMS that passed away 3 years later due to tumor progression without undergoing postoperative radiotherapy and chemotherapy. Tessho Maruyama [17] found that the recurrence rate of LGMS patients after surgery alone was 18.8%, while the recurrence rate after surgery combined with radiotherapy was 71.4%. This suggested that postoperative radiotherapy for LGMS may contribute to tumor recurrence, and it was recommended to avoid radiotherapy after LGMS resection. Ni [12] et al. suggested that the treatment of LGMS requires extensive resection, confirming that there was no residual tumor in the margin of resection, and performing postoperative radiotherapy and chemotherapy if necessary. Therefore, the treatment method should be selected according to the tumor location, size, and degree of invasion. Complete intraoperative resection was used in this case, and there was no sign of recurrence after 1 year of outpatient follow-up.