Abstract: Objective:To analyze the clinical features and treatment methods of one infant with low-grade malignant myofibroblastic sarcoma(LGMS) in the left temporal region, and to provide the basis for its diagnosis. Methods:The clinical data of one infant with LGMS in the left temporal region were collected, and the clinical features, diagnosis and treatment of the patient with LGMS were analyzed combined with the relative literatures. Results:A 4-month-old infant was admitted because of left temporal mass for 20 d. The CT image showed a subcutaneous space-occupying lesion in the left temporal region, the CT value was 20-40 HU, and the size was about 2.0 cm×2.0 cm×2.0 cm and the lesion invaded the skull. The enhanced MRI images showed an irregular lesion in the left temporal region, the lesion invaded the skull, the border with the surrounding brain tissue was still clear, the size was about 1.9 cm×1.6 cm×2.0 cm, and the T1WI, T2WI and FLAIR results presented as isointensity in the lesion. The lesion showed inhomogeneous enhancement.The CT and MRI results showed that the subcutaneous tumor invaded the skull, suggesting that there may be malignant tumor. The patient underwent left temporal subcutaneous intracranial and extracranial mass operation to completely resect the lesion, and the pathological diagnosis was LGMS. The patient did not receive radiotherapy or chemotherapy after operation. There was no recurrence after follow-up for 16 months. Conclusion:LGMS is a kind of invasive tumor without specific imaging findings. Total resection is an effective treatment. The pathological diagnosis is the gold standard for the diagnosis of LGMS. The LGMS patients should be given regularly follow-up after operation.

Key words: low-grade myofibroblastic sarcoma, infant, left temporal region, case report