Low-Grade Fibromyxoid Sarcoma Incidentally Discovered as a Hip Mass: A Case Report.

Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft tissue malignant tumor that presents as a slowly enlarging painless mass that is difficult to differentiate from other neoplasms. A 56-year-old woman presented to our clinic with a soft mobile mass in the left buttock and ipsilateral lower limb stiffness. Ultrasonography revealed a hypoechoic mass in the gluteus maximus adhering to and compressing the sciatic nerve. Ultrasound-guided biopsy indicated that the tumor consisted of spindle cells featuring mucinous metaplasia. Postoperative pathology confirmed LGFMS. Postoperative follow-up showed good recovery and no sciatic nerve compression. This case presents an effective approach to diagnose LGFMS.