The cyst of the canal of nuck: a great mimicker of groin hernia in female

A 38-year-old female presented to the outpatient clinic with a progressively enlarging, painless right inguinal swelling that had been present for several years. There was no past medical history of trauma, infection, or inguinal surgery. Upon physical examination, the longest dimension of the inguinal swelling was measured at about 6 cm. The mass showed no symptoms of irritation or pain, and it was movable and irreducible. The position and features of the enlargement initially led to the clinical impression of an inguinal hernia. However, the irreducibility of the mass prompted further investigation. An MRI of the soft tissues was performed. The latter revealed a well-defined, purely cystic lesion. In T1-weighted images (Fig. 1a), the cyst showed hypointense signals, and in T2-weighted images, hyperintense signals (Fig. 1b). Additionally, the cyst contained thin, regular septations with a thin wall showing slight enhancement after gadolinium injection. The cyst measured 44 × 22 mm in the axial plane and extended longitudinally for 83 mm. It was observed passing through the inguinal canal and terminating near the ipsilateral labia majora. These imaging features suggested the presence of a Nuck canal cyst. An open surgical procedure was chosen to be carried out. In line with the MRI results, the cyst was discovered to be expanding through the inguinal canal during surgery. It was meticulously dissected from the surrounding structures, including the round ligament and inguinal vessels and then it was ligated and entirely excised (Fig. 2). The cyst was removed intact, ensuring that no residual cystic tissue was left behind to prevent recurrence. By suturing the external abdominal oblique tendon to the inguinal ligament's shelving edge, the internal inguinal ring defect was repaired. The pathology report confirmed the diagnosis of a hydrocele of the canal of Nuck, with no evidence of malignancy or infection. Clear serous fluid was seen within the cyst wall, which was bordered by a thin layer of mesothelial cells. During her nine-month follow-up, the patient was doing well after surgery and showed no evidence of recurrence. The cyst of the canal of Nuck is a rare condition in females, equivalent to a male hydrocele, resulting from incomplete obliteration of the processus vaginalis which normally disappears in the first year of life.1 Unknown causes typically result in an imbalance between the secretory membrane's absorption and secretion, which is the likely reason of the cyst formation. It typically presents as a groin lump and is often misdiagnosed due to its rarity.2 While physical examination may provide some clues, imaging studies such as ultrasound or MRI are often necessary for a definitive diagnosis.3 A systematic review identified 16 case reports in adult females, with a mean age of 35.18 years, predominantly affecting the right side.4 Treatment options include open or laparoscopic surgical approaches, with various techniques such as hydrocelectomy, cystectomy with or without hernia repair, inguinal ring ligation, round ligament excision, and vulva correction in some cases.4 Three types of hydrocele of the canal of Nuck have been identified: hourglass, communicative, and encysted.5 Increased awareness and recognition of this condition among clinicians, radiologists, and surgeons are essential to prevent unnecessary procedures and ensure optimal patient outcomes. Imen Ben Ismail: Conceptualization; data curation; resources; writing – original draft. Marwen Sghaier: Investigation. Saber Rebii: Supervision. Hakim Zeznaidi: Supervision. Ayoub Zoghlami: Validation. Written informed consent was obtained from the patient for the publication of this case report and the accompanying images.