Objective: To identify any risk factors that may relate to post-ear piercing keloid formation.

Materials and Methods: This case control study was conducted in Thai people at Department of Plastic and Maxillofacial Surgery at Ramathibodi Hospital between August 2015 and August 2016. It consisted of post-ear piercing subjects with and without keloid formation as case (43 subjects) and control (44 subjects) groups respectively. Information regarding age at piercing, history of keloid formed, age of keloid formation, site of piercing, method for piercing, jewelry use after piercing, complications, development of keloid at other location of the body, family history of keloid, and skin color was collected.

Results: According to the study, complications from piercing such as infection or allergic reaction were significantly related to post-ear piercing keloid formation (p<0.001). Piercing through cartilage was also proven to be one of the major risk factors (p<0.001). There was no difference between cases and controls in terms of age at piercing, method for piercing, use of jewelry, keloid at other location of the body, family history of keloid, and skin color.

Conclusion: Two major contributing factors of post-ear piercing keloid formation that were identified from the present study are development of post-piercing complications and cartilage piercing.

Keywords: Keloid, Ear piecing, Risk factors, Skin color, Cartilagenous part