1576 Indian Journal of Forensic Medicine & Toxicology, July-September 2020, Vol. 14, No. 3 The Role of Fractional CO 2 Laser in Treatment of Keloid and Hypertrophic Scar used Alone and in Combination with Intralesional Steroids Nadia H. Sahib 1 , Mohammed K. Al-hattab 2 , Fatin Ahmed Fakhry 3 , Ihsan Jara Atiyah 4 1 Lecturer, 2 Prof. Dr., 3 Bachelor of Medicine, University of Babylon – Hammurabi Medical College, 4 Iraqi Board for Medical Specializations, Imam Al-Sadiq Teaching Hospital Abstract Background: The hypertrophic and keloid scars are thick , raised, disfguring areas of skin with abnormal prolonged infammatory response of wound healing process and overproduction of collagen. Carbon dioxide (CO 2 ) laser has been used in the treatment of hypertrophic scar and keloids for more than 20 years. Aim of Study: To evaluate the effect of (CO 2 ) laser in treatment of keloid and hypertrophic scar with use of intralesional triamcinolone acetonide (kenacort) 40 mg/ml as adjuvant therapy. Methodology: The study was done on 22 patients in Imam al-Sadiq teaching hospital in Hilla city with dividing the patients randomly in to two groups ,one group treated with four sessions of intralesional corticosteroids and the second group treated with four sessions of intralesional corticosteroids with carbon dioxide laser. Keywords: Hypertrophic scar, Keloid scar , CO 2 laser, Corticosteroid. Introduction The scar is an area of fbrous tissue that replace the normal skin tissue after an injury. Deregulation of the process of wound healing that is complex , regulated response to the injury leads to development of scar. Despite both hypertrophic and keloid scar are common but the keloid scar is more challenging to treatment and may have signifcant physical and psychological impacts on patients life 1 . The scar biology is less well understood till now and search for the ideal treatment still continues and despite the different types of treatments including radiation, pressure therapy, cryotherapy , intralesional steroid or interferone, topical silicon and many other lines of treatment , no one is 100% curative as the frst line treatment 2 . Parameters that used to assess the scar clinically involve scar colour, blood fow, erythema, itching, skin hardness, extension beyond the wound margin and healing spontaneously 3 . Hypertrophic scar is more common than keloid. Its erythematous, itchy, elevated lesion and less nodular than keloid scar and it is not extend beyond the wound margin and may heal alone and its size depends on the size and depth of the original wound 4 . The origin of word keloid from the Greek word Chele which means pincers of crab, the suffx oid means like, so it called keloid because it grows in pincers of crab like lesion 5 . Keloid scars are erythematous, nodular lesions extend beyond the margin of the injured site and not regress spontaneously 6 . The pathogenesis of keloids involve hyperprolifrative state due to abnormal molecular and cellular driving with four folds decrease in cell apoptosis and increase in survival marker AKT 7 . Keloid scar may develop due to trauma ,burn , injury or spontaneously as reported in patients with bethlem myopathy due to mutation in collagen type four 8 . Hypertrophic scar results from injury,burn,surgery and unlike keloid scar, it is more linear in nature and within the wound margins 9 . Keloid is a dermal lesion with excessive collagen and glycosaminoglycan around the wound with increase tissue growth factor B1 and the studies show increase in the incidence of keloid in patients who receive tissue growth factor B1 treatment and decrease incidence in those who receive anti tissue growth factor B1 10 . Keloid is common in young