Classic Low-Grade Fibromyxoid Sarcoma: A Case Report and Literature Review

Background: The low-grade fibromyxoid sarcoma (LGFMS) is an exceptionally uncommon sarcoma that primarily manifests in the extremities or trunk of young adults, presenting as painless lesions. The histological features of this tumor are benign, but it exhibits an exceptionally high rate of late recurrence and a significant potential for metastasis. Imaging examinations serve as a crucial method for detecting LGFMS, while the definitive diagnosis relies on histopathological assessment. Currently, the primary treatment modality for this neoplasm is surgical resection. Early aggressive surgery with negative margins is a critical factor in mitigating the risk of tumor recurrence and metastasis. The present study presented a case of LGFMS located in the right thigh. The patient underwent a mass resection procedure following an MRI examination. During the telephone follow-up one year post-surgery, despite the absence of an imaging review, the surgical site demonstrated satisfactory recovery with no reported abnormal symptoms. Case Presentation: The patient, a 31-year-old male, presented to our hospital for evaluation of an asymptomatic mass in his right thigh that was incidentally discovered 13 years ago. The MRI showed a well-defined mass measuring 8.2 cm × 6.8 cm × 9.6 cm in the right thigh. The tumor signals exhibit a mixed pattern, characterized by predominantly isointense and hypointense signals on T1-weighted imaging (T1WI), a central area of hyperintensity on T2-weighted imaging (T2WI), and peripheral circular enhancement observed on contrast-enhanced scans. The patient underwent surgical resection. Microscopically, the mass was composed of intricately interwoven fibrous matrix and a distinct mucoid region. The tumor cells exhibited a distinctive arrangement in a swirling or wheel-like pattern, with minimal variation in their karyotypic characteristics. The immunohistochemical examination revealed diffuse and intense MUC4 positivity in the tumor cells. The diagnosis of LGFMS was confirmed by post-operative histopathological examination. Conclusions: The LGFMS is an exceptionally uncommon mesenchymal tumor renowned for its benign histological manifestations and malignant behavior. It is crucial to provide a comprehensive summary of the research findings and thoroughly review the existing literature pertaining to this rare disease.