Epidermoid cyst at a rare location, as a content of inguinal hernia: A case report with a review of the literature.

A 29-year-old female presented with a lump in the left inguinal region for the last 4 years. She experienced mild, occasional pain on standing for a long time. On examination, the lump was found to be non-tender and partially reducible, and cough impulse was present, getting above the swelling was negative. Abdominal examination showed no other abnormality. Clinically, it was diagnosed as left inguinal hernia. The patient was planned for an elective totally extra-peritoneal (TEP) mesh repair after routine preoperative investigations. During surgery a large mass of about 11 cm × 5 cm was found in the left inguinal region, extending from the deep inguinal ring to beyond the superficial inguinal ring. Intraoperatively, the mass seemed to be a cystic lesion and was attached to the left round ligament within the inguinal canal [ Figure 1 ]. The operative approach was changed to trans-abdominal preperitoneal (TAPP) repair due to the large size of the mass and to view the intra-abdominal organs to trace the site of origin. Intra-abdominal organs such as the uterus, ovaries and its ligaments were normal and the cystic mass was only attached to the round ligament in the left inguinal canal. The cystic mass was completely mobilised and excised laparoscopically. Polypropylene mesh (Prolene ® , Ethicon) of 15 cm × 13 cm size was placed for hernia repair at the left myopectineal orifice. The excised mass [ Figure 2 ] was sent for histopathological examination and was reported to be epidermal inclusion cyst [ Figure 3 ]. The patient was discharged on post-operative day 1. Cystic mass attached to the round ligament in the left inguinal region Cut section of excised cystic mass 200×, HE stain, Stratified squamous lined cyst filled with acellular lamellated keratin material without any calcification

Intra-abdominal organs and small or large bowel as content of inguinal hernia is common but epidermoid cyst as content of inguinal hernia is very rare. Epidermoids are benign cystic lesions of the skin. They are usually located at the intradermal or subcutaneous region and formed by invagination of keratinized squamous epithelium.[ 1 ] Epidermal cysts can be located in any part of the body, commonly on the face, torso, extremities and scalp. It has not been reported in the inguinal canal as content so far. Eleven cases of dermoid cysts of the inguinal canal have been reported. Other rare contents of the inguinal canal are teratoma, lipoma, lymphangiomas, leiomyoma and endometriosis.

Inguinal hernia commonly present as inguinal swelling. Other common swellings in the inguinal region include undescended testes, lipoma and hydrocele. Epidermoid cyst is an extremely rare content of inguinal hernia. No case has been reported so far on epidermal inclusion cyst (epidermoid cyst) as content of inguinal hernia. In this patient, the cystic mass was excised laparoscopically and mesh repair was performed. Eleven cases of dermoid cyst as a content of inguinal hernia have been reported.[ 2 ] Teratoma of the inguinoscrotal region is relatively common. Grossly, the dermoid cyst and epidermoid cyst may look similar but they differ microscopically. Both are ectoderm-lined inclusion cysts that differ in complexity. Epidermoids have only squamous epithelium while dermoids contain hair, sebaceous glands, sweat glands and squamous epithelium. Both arise from trapped pouches of the ectoderm, near-normal folds or from failure of the surface ectoderm to separate from the neural tube.[ 3 ] Presence of the skin, along with its appendages and sebaceous gland, differentiates dermoids from epidermoid cysts that have stratified squamous epithelium surrounded by fibrous tissue forming their wall. Epidermoid cyst may result from the sequestration of epidermal nests during the embryonic life, occlusion of the pilosebaceous unit, or traumatic or surgical implantation of epithelial elements. Teratomas are true neoplasms arising from misplaced embryologic germ cells. They contain a medley of heterogeneous tissues, typically reflecting more than one of the three embryonic germ layers.[ 3 ] Teratomas may be benign or malignant. Other rare swellings reported in the literature include preperitoneal lipoma,[ 4 ] inguinal lymphangioma,[ 5 ] round ligament leiomyoma[ 6 ] and inguinal endometriosis.[ 7 ] Nil. There are no conflicts of interest.