Endometrioma of the Rectus Abdominis Muscle: US Features

Endometrioma in the rectus abdominis muscle is a rare condition. The disease presents in a population of mostly young females of child-bearing age, often with previous history of Cesarean section or gynecological surgery. It is defined as the presence of endometrial tissue outside the uterine cavity. The sonographic appearance is variable. Common sonographic findings are a hypoechoic mass with inhomogeneous echo texture, scattered hyperechoic echoes and irregular margins, as well as solid or cystic lesions. A hyperechoic ring often notes inflammatory alterations. Internal vascularization can be detected in almost every case. Ultrasound is often the first diagnostic tool. Abdominal CT or MR can prove useful in the differential diagnosis. FNAC should be avoided, as spreading of the tissue can occur. It should be noted that neither of the imaging modalities can provide a certain pre-operative diagnosis. The final diagnosis is made by pathological examination after surgical excision of the lesion. The differential diagnosis can be difficult, and includes ventral hernia, hematoma, lymphadenopathy, lymphoma, lipoma, abscess, subcutaneous or sebaceous cyst, suture granuloma, soft-tissue sarcoma, desmoid tumors, and even metastatic cancer. Surgical excision provides the best therapeutic option. In the absence of a suggesting clinical history, the differential diagnosis can be difficult.

The authors declare that they have no competing interests.