EP20.05: Magnetic resonance imaging of abdominal wall endometriosis clinically and sonographically mimicking a tumour

A 38-year-old lady presented with insidious onset of a left anterior lower abdominal mass next to the Caesarean scar for seven years. Physical examination reviewed a 3-cm hard tender mass at the left anterior abdominal wall. Ultrasound reviewed a hypoechoic subcutaneous lesion of lobulated contours (yellow arrowheads) showing only mildly increased colour Doppler signals (purple arrows) with no clear fascial plane with the left rectus abdominis muscle (green arrows) at the site of the patient's concern. The clinical and ultrasound diagnosis was a malignant tumour. MRI showed small foci demonstrating blooming artefact on gradient recalled echo sequence and T1 hyperintense signals on the fat-suppressed sequence within the lower anterior abdominal lesion, corresponding to the site of the clinically and sonographically detected mass. No pelvic solid mass was evident. Cytological examination of the abdominal wall lesion showed strips of glandular epithelium accompanied by endometrial-type stroma being positive for estrogen receptor. The overall features are consistent with endometriosis. Abdominal wall is an atypical site of endometriosis. Although the ultimate diagnosis requires histological examinations, imaging is helpful in localisation and characterisation of the disease. MRI is more specific than ultrasound and physical examination in evaluation of abdominal wall endometriosis. Hyperintense contents on fat-suppressed T1&2 weighted images and blooming artefact on gradient recalled sequence suggest the presence of methemoglobin and hemosiderin respectively and help excluding fat-containing diseases such as lipoma. Supporting information can be found in the online version of this abstract Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.