Dermoid cysts are developmental lesions occurring along the line of embryonic fusion. [1] Common sites include supraorbital region of forehead and midline. [1] Dermoid cyst of anterior abdominal wall is rare. Literature review revealed only five cases of inguinal dermoid till date. [1] [2] [3] [4] [5] [6] [7] We report a case with review of literature.

A 48-year-old male patient presented with a swelling in left groin since last 12 years. The swelling was progressive in nature, increased in size on straining, coughing and decreased on lying down. It was associated with occasional pain which subsided on medication.

Physical examination revealed mild pallor with a left sided inguinoscrotal swelling. The swelling extended from mid inguinal region to root of left scrotum. It was pyriform shaped and measured 10 cm in its longitudinal axis. We could not get above the swelling. Cough impulse was present. The swelling was doughy on palpation. It was irreducible. Abdominal and per-rectal examinations were within normal limits. A clinical diagnosis of Irreducible left inguinal hernia was made and an elective inguinal hernioplasty was planned.

Laboratory investigations reveled a hemoglobin- 9 g/dL, WBC count- 11,000/mm³, DLC-N₆₃L₃₀E₇, 63%, L 30%, E 7%), blood glucose 110 g/dL, urea 20 mg/dL, serum creatinine 0.8 mg/dL. Chest X-ray and ECG were normal.

Exploration of the left inguinal canal revealed a cyst (10x7 cm) in the floor of the inguinal canal separated Exploration of the left inguinal canal revealed a cyst (10x7 cm) in the floor of the inguinal canal separated from the cord structures. The cyst extended from the deep ring above to upper pole of left testis below. Cord structures were separated from cyst. No direct or indirect sac could be detected. The cyst was opened and foul smelling muddy paste like material along with a few hairs (Figure 1) came out. Cyst was completely excised and sent for histopathology. The postoperative recovery was uneventful and the patient was discharged on 10th post operative day after stitch removal.

Histopathology revealed a thin-walled cystic lining composed of keratinized squamous epithelial cells. Underlying layers contained blood vessels, hair follicles, ecrine and apocrine glands. The above findings were consistent with a dermoid cyst.

The patient is doing well at one year follow-up.

Hernia is the commonest inguinal swelling. Other common swellings include undescended testes, lipoma or hydrocele of spermatid cord. Rare inguinal swellings include preperitoneal lipoma, supernumerary pectineus bursa, haemorrhage into internal internal oblique muscle, round ligament angioma, pedunculated uterine fibromyoma, inguinal endometriosis and thrombophlebitis. [5]

Dermoid cyst as a cause of inguinal swelling is rare. A search of English medical databases, using key words dermoid cyst and inguinal mass, revealed five case reports of inguinal dermoid till date (Table 1). [2] [3] [4] Of the five patients three were female [2] [3] and two male. [4] Four patients were below 30 years [3] [4] of age and the fifth patient was 72 years of age. [2] The duration of the swelling varied from 1 to 4 years. The swellings were provisionally diagnosed as inguinal hernia, [2] [4] lipoma [3] and cyst of the round ligament respectively. Dermoid cyst was revealed peroperatively and confirmed histopthologically. A fifth patient had dermo-plastic repair of inguinal hernia and later developed inclusion dermoid. [7]This procedure is obsolete and as such does not need further elaboration

Dermoid cysts may be teratomatous or non teratomatous benign malformations. [3] [4] [5] Non teratomatous dermoids are common in the inguinal canal. Grossly the excised tumour may be mistaken for a sebaceous cyst or epidermoids. The microscopic presence of skin along with its appendages and sebaceous gland differentiates them from epidermoids and sebaceous cyst which have stratified squmaous epithelium surrounded by fibrous tissue forming their wall. [2] [3] [4] The absence of tissues foreign to the part differentiates it from a true dermoid found elsewhere. The contents of the cyst have been reported as tan-colored keratin resulting from accumulation of stratum corneum. [4]

Diagnosis is often mistaken clinically as irreducible inguinal hernia. Complications of the cyst which resembles obstructed or incarcerated inguinal hernia include inflammation and hemorrhage. [4] The cyst may sometimes lead to compression of adjacent organs causing retention of urine and bowel obstruction. [4] The possibility of malignant degeneration exists especially in women with dermoid cysts arising from round ligament. [6] Tumor markers like alpha fetoprotein and beta chorionic gonadotropin estimation are helpful to monitor treatment and recurrence. [6]

Surgical excision is the treatment of choice. [1] [2] [3] [4] [5] [6]

Inguinal dermoid cyst is rare. If encountered complete excision is to be contemplated in order to avoid complications like-inflammation, hemorrhage and rarely malignant degeneration.

1. Genetzakis M, Lagoudianakis EE, Papadima A, et al. Inguinal dermoid cyst of the round ligament. A case report and review of the literature. Clin Exp Obstet Gynecol 2006;33:249–51.   [Pubmed]    
2. Brightmore T. Dermoid cyst of the inguinal canal simulating a strangulated inguinal hernia. Br J Clin Pract 1971;25:191.   [Pubmed]    
3. Ashraf SM, Ansari BA, Iqbal N, Ansari A. Dermoid cyst of the inguinal canal. J Indian Med Assoc 1985;83:125–6.   [Pubmed]    
4. Leeming R, Olsen M, Ponsky JL. Inguinal dermoid cyst presenting as an incarcerated inguinal hernia. J Pediatr Surg 1992;27:117–8.   [CrossRef]   [Pubmed]    
5. Farrands PA, Taylor I. Unusual groin swellings. Postgrad. Med J 1984;60;309–11.   [CrossRef]   [Pubmed]    
6. Khvorostov ED, Zakharchenko IuB, Tomin MS. Dermoid cyst of inguinal channel: review of the literature and clinical Observation. Klin Khir 2008;3:20–2.   [Pubmed]    
7. Doctor HG, Talwalkar MG, Raichur BS. Inclusion dermoid cyst following repair of hernia with full thickness skin graft. Report of a case and review of the literature. J Int Coll Surg 1963;40:109–6.   [Pubmed]