Caecal Dermoid Cyst: A Right Iliac Fossa Diagnostic Dilemma

Abstract

Mesenteric dermoid cysts are rare extragonadal mature cystic teratomas and may present as cystic lesions in the right iliac fossa. Their clinical and radiological features are often non-specific, and preoperative distinction from more common ileocaecal and appendiceal pathology may be difficult. We report the case of a 25-year-old male who presented with intermittent dull aching pain in the right iliac fossa for two weeks, without fever, vomiting, altered bowel habit, gastrointestinal bleeding, anorexia, or weight loss. Routine haematological and biochemical investigations were within normal limits. Contrast-enhanced computed tomography demonstrated mild mural thickening of the terminal ileum and ileocaecal junction, with a well-defined 2.5 x 2.7 cm cystic lesion abutting the caecum and anterior abdominal wall. Magnetic resonance imaging showed a T2 hyperintense cystic lesion closely related to the caecum, and appendiceal mucocele and infected enteric duplication cyst were considered the principal differential diagnoses. Colonoscopy showed normal colonic and terminal ileal mucosa. Diagnostic laparoscopy identified a 5 x 3 cm cystic lesion arising from the inferior surface of the caecum, with dense central adherence to the caecal wall. Stapled wedge resection of the involved caecal segment with appendectomy was performed, and the specimen was retrieved without intraperitoneal spillage. Histopathological examination showed keratinised stratified squamous epithelium, focal sebaceous glands, and keratinous debris, confirming a mature cystic teratoma (dermoid cyst). No immature elements or malignant transformation were identified. The postoperative course was uneventful, and the patient remained asymptomatic at follow-up. This case highlights the diagnostic difficulty of caecal and mesenteric dermoid cysts and supports complete surgical excision with histopathological confirmation.