Mesothelial cyst of the round ligament mimicking a metastasis: a case report

Abstract

A mesothelial cyst of the round ligament is a rare cause of an inguinal mass. Clinically, it is frequently misdiagnosed as one of commoner diseases such as an inguinal hernia, femoral hernia, lipoma, and lymphadenopathy upon physical examination. Some previous reports elaborated the sonographic features of a mesothelial cyst of the round ligament. However, to our knowledge, few reports have described the CT features of a mesothelial cyst. We illustrated here the sonographic and multidetector CT features of a case of a mesothelial cyst of the round ligament that presented as an inguinal palpable mass and mimicked a metastasis in a patient with a Sertoli-Leydig cell tumor of the ovary.

Keywords: Inguinal area; Mesothelial cyst; Multi-detector row CT; Round ligament; Ultrasonography.

Fig. 1

Mesothelial cyst of round ligament in 76-year-old woman. A. Sagittal ultrasound shows well-circumscribed, oval cystic mass with hypoechoic solid portion (arrows) at left inguinal region. In addition, stalk-like structure (arrowheads) in cranial aspect of mass was also observed. B. Color Doppler ultrasound shows flow signals (arrows) in solid portion and walls of mass. C. Axial contrast enhanced CT shows left inguinal cystic mass (arrows) with hypertrophic wall and internal enhancing solid portion. D. Coronal contrast enhanced CT shows 21×12×10 cm sized multi-locular, well-circumscribed, complex cystic and solid mass (white arrows) extending from right adnexa to upper abdomen. Left inguinal cystic mass (asterisk) was abutted to extraperitoneal portion of round ligament (arrowheads). E. Left ovarian vessels (arrowheads) are located apart from inguinal cystic mass. In addition, unusually thick, round ligament (arrow) is noted just proximal to inguinal canal. F. Photomicrograph showing diffuse stromal edema, inflammatory cell infiltration, and mesothelial cell proliferation in round ligament adjacent to cyst lined by mesothelial cells (Hematoxylin & Eosin staining, ×100). Immunostaining of WT-1 and mesothelial cell marker highlight cyst-lining mesothelial cells (arrow) (inset, ×200).