LAUSR

Introduction and importance A canal of Nuck cyst forms because of a patent peritoneal fold evaginating through the inguinal canal in a female patient. It is a rare diagnosis because the canal often obliterates within the first year of a female patient's life. A persistent canal of Nuck may cause indirect inguinal hernias, or form hydroceles, termed canal of Nuck cysts. Here we report the first case of a canal of Nuck cyst discovered to be evaginating through the femoral canal. Case presentation A 70-year-old female patient initially presented with a symptomatic groin mass, and a suspected inguinal hernia on pre-operative ultrasound. Intraoperatively, she was found to have a canal of Nuck cyst terminating within the femoral canal. This was successfully repaired using a modified McVay approach, and approximation of the internal inguinal ring. She performed well post-operatively with no signs of recurrence at her six-month follow-up. Clinical discussion This case report serves to highlight the canal of Nuck cyst, a rare embryologic remnant, and the first literature-reported femoral canal of Nuck cyst. We re-affirm the diagnostic unreliability of ultrasound imaging in the workup of groin hernias. Furthermore, we describe surgical techniques to repair a canal of Nuck cyst found within the femoral canal. Conclusion To the best of our knowledge, no prior literature reports a canal of Nuck cyst presenting as a femoral hernia. This rare diagnosis may be encountered in common operations and is amenable to definitive repair using traditional hernia repair techniques.