Delayed presentation of an iatrogenic postauricular epidermal inclusion cyst after ear surgery: a case report.

Epidermal inclusion cysts (EICs) are slow-growing, non-malignant lesions typically arising from entrapped epidermal cells within the dermis. While commonly seen in areas such as the face and neck, their occurrence behind the ear is uncommon. In rare instances, EICs may develop after surgery due to the unintended implantation of skin epithelium during the closure process. We describe a 26-year-old male who developed a gradually enlarging mass in the left postauricular area, 2 years following tympanoplasty. The patient reported no associated symptoms or trauma. The physical examination revealed a firm, tender swelling without any skin changes. Imaging indicated a soft tissue lesion with mastoid sclerosis. Initial antibiotic therapy was ineffective. Surgical exploration revealed a cystic structure, which was completely removed. Histological evaluation confirmed an EIC with no malignant features. The patient recovered without complications. This case illustrates a rare postoperative occurrence of an EIC following ear surgery. Given the potential for such lesions to mimic other conditions, clinicians should maintain a broad differential diagnosis. Proper surgical closure technique may help reduce the risk of epithelial cell entrapment. Complete excision remains the definitive treatment for preventing recurrence and ensuring optimal patient outcomes.