Cyst of the canal of nuck: A rare cause of inguinal swelling in women

Nuck canal can be defined as the abnormal persistence of processus vaginalis opening in female inguinal canal.[] It was first described by anatomist Anton Nuck in 1691. Peritoneum which follows round ligament, through inguinal canal to labia major forms this canal and it is the counterpart of processus vaginalis in males. It generally closes within eighth month of gestation. Inadequate closure of this canal leads to indirect hernia or rarely hydrocele of Nuck canal.[] Cyst of the canal of Nuck or female hydrocele are other names used for this disease. There are only few case reports present for adults in the literature. Once diagnosed surgical excision is the definitive treatment. Here we present 26-year-old female who was operated for Nuck canal cyst. CASE REPORT A 26-year-old female presented with a right groin swelling which she noticed one month ago. No medical history of trauma, infection, constipation, or other causes of abdominal pressure increase were present. She had pain for 10 days and swelling increased in size. Patient's menstrual periods were regular. Physical examination revealed 3 × 3 cm palpable irreducible mass with fluctuation. Ultrasonography revealed 36 × 20 × 38 mm cystic mass at the right groin with hemorrhagic, echogenic fluid level inside with septal vascularization. Because of patient intolerance to magnetic resonance imaging (MRI), abdominal computed tomography (CT) performed and reported a right inguinal hernia. The CT findings are given in Figure 1. Cystic lesion extending toward to the labia was resected by open right inguinal approach and the patient was discharged without any complication. Intraoperative finding is given in Figure 2. Histopathological examination showed multicystic inflamed structure lined with mesothelium. Immunohistochemical studies revealed D2-40 and WT-1 positive CD-31 negative staining which showed that epithelium derived from mesothelium. Histopathological findings are given in Figure 3.

Cyst of Nuck canal is an uncommon reason of female inguinal region abnormalities. The actual incidence is not known. It is mostly present in the first year of life. Inguinal hernia, endometriosis, Bartholin cysts, inguinal lymphadenopathy, and tumors (malign or benign) must be considered in differential diagnosis in adult patients. Radiological studies can be helpful. Ultrasound has advantages of wide availability, lack of radiation exposure with low cost, and should be primary imaging modality.[] In case of suspicion for other diseases abdominal CT or MRI can be useful. MRI gives valuable information about the relation of the lesion and peritoneal cavity.[] Proximal closure of processus vaginalis and fluid deposition in the distal part forms a cyst in the inguinal canal. Histopathological examination confirms epithelium-lined true cyst formation. Besides cyst formation some benign (lipoma, leiomyoma, desmoid tumors, endometriosis, etc.) or malign tumors (liposarcoma, leiomyosarcoma, endometrioid carcinoma, etc.) can arise from Nuck canal.[] Differential diagnosis is important for optimal treatment. Although aspiration of cyst material in asymptomatic patient is possible recurrence is common. Surgical exploration is crucial for diagnosis and excision of the cyst with the high ligation of the canal with repairment of hernia if present is the definitive treatment of Nuck canal cysts.[]

Nuck canal cyst is a rare entity and must be considered in differential diagnosis of female inguinal region swellings. Surgical intervention can provide definitive treatment. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

- 1. Nasser H, King M, Rosenberg HK, Rosen A, Wilck E, Simpson WL. Anatomy and pathology of the canal of Nuck Clin Imaging. 2018;51:83–92 - 2. Caviezel A, Montet X, Schwartz J, Egger JF, Iselin CE. Female hydrocele: The cyst of Nuck Urol Int. 2009;82:242–5 - 3. Lai I, Page A, Hamidinia F, Rahmani R. Cysts of the canal of Nuck: A rare sonographic diagnosis J Clin Ultrasound. 2017;45:175–8 - 4. Choi YM, Lee GM, Yi JB, Yoon KL, Shim KS, Bae CW, et al Two cases of female hydrocele of the canal of Nuck Korean J Pediatr. 2012;55:143–6 - 5. Rees MA, Squires JE, Tadros S, Squires JH. Canal of Nuck hernia: A multimodality imaging review Pediatr Radiol. 2017;47:893–8 - 6. Okoshi K, Mizumoto M, Kinoshita K. Endometriosis-associated hydrocele of the canal of Nuck with immunohistochemical confirmation: A case report J Med Case Rep. 2017;11:354