The occurrence of endometriosis as a soft tissue tumor in orthopaedics is rare. We present a patient who had endometriosis in the inguinal subcutaneous region.
A thirty four-year-old woman noticed a bean-sized tumor in the right inguinal region in 1982. The tumor responded to antibiotics. A bean-size painful tumor was again noticed in the same region in 1993. The mass and the pain were more prominent just after menses. Rediographs were normal. A subcutaneous soft tissue tumor with a 2.5cm in diameter could be seen on computed tomographic scans. On MRI the tumor was segmented, not enhanced with contrast medium, and demonstrated, moderate to high intensity on T1-weighted images and high intensity on T2-weighted images. Histological examination of the biopsy specimen revealed endometrial glands and stroma. We diagnosed endometriosis of the inguinal region and resected widely. Six months after the operation, the patient was asymptomatic and had resumed all of her usual activities.
Several cases involving endometriosis have been reported in Japanese orthopaedic articles, so it is important to remember endometriosis in the differential diagnosis of soft tissue tumors.
