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

ABSTRACT 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.