Chemical peeling - Glycolic acid versus trichloroacetic acid in melasma

Introduction

Melasma, one of the common aesthetically displeasing entiy, continues to be a difficult problem to treat.[1] Different topical depigmenting agents have been used alone or in combination with varying results but no agent has proved to be idea 1.[2],[3],[4] Chemical peeling is one new weapon in the therapeutic armamentarium. Chemical peeling has been used in different dermatologic conditions[5],[6],[7],[8],[9],[10] with encouraging response. Various chemical agents have been used and each has its own peculiar features and produces peeling of different depths.[11],[12]

Glycolic acid and trichloroaceic acid have been used alone and also in combination to treat melasma[13],[14] but no study compares the individual effects of these agents in this condition.

Materials and Methods

One hundred cases of melasma, attending the OPD of Skin, STD and Leprosy, Dr. S.N. Medical College, Jodhpur, were included in the study. All these patients were screened and underwent detailed clinical history including duration of disease, evolution, precipitating/aggravating factor or other associated illness, previous treatment taken, if any.

Only those cases not responding to conventional therapy at least for last 6 months were included. Patients with any history of active herpes simplex, keloidal tendency or unrealistic expectations were not taken. Clinical photographs at the beginning of therapy and then serially, were taken to assess the clinical response.

Prior to application, a written informed consent was obtained. A post auricular test peel was performed and left for 15-20 minutes to find any hypersensitivity to the ingredients of peeling agent. Patients were divided into two groups, one receiving glycolic acid (GA) 55-70% and other trichloroacetic acid (TCA) 10-15%. GA and TCA groups comprised of 68 and 32 cases respectively.

Applications were made every 15 days i.e. on a fortnight basis till significant improvement occurred or otherwise. Response was assessed by three main criterion-clinical photographs, subjective improvement as experienced by patient and clinical response as assessed by physician.

Before application of peeling agent, patients were advised to wash the face with soap and water. After patting the face dry, cleansing was done with spirit and then acetone soaked sponges to remove all cutaneous oils. GA and TCA were applied with cotton buds/gauze with mild strokes. After a contact period of 5-10 minutes neutralization was done with cold water. Post peel topical sunscreens were advised.

Observation

It was observed that melasma was more frequent in women as compared to men M:F ratio being 1:1.6. Most patients were of younger age group 87% between 20-40 year with maximum number 54% in 20-30 years. 40% patients had duration of onset of less than 1 year whereas 32% had pigmentation for more than 3 years [Table - 1]. Sun exposure was the main precipitating factor (28%) followed by pregnancy and drugs [Table - 2]. Exacerbation with sunlight was seen in all cases. Associated facial dermatoses were also seen-acne/acne scars (30%), viral warts (7%), seborrheic keratosis (5%) and milia (5%). Forty-eight percent of patients required less than 5 peel whereas 46% 5-10 peel. GA required more number of peel (average 6.1) as compared to TCA (4.1) for the response. Significant> 75% improvement was seen in 30% of total patients and 50-75% improvement seen in 24% patients. In GA group < 25% response was seen in 27.9% patients, as most patients left the study after 1 or 2 peel owing to slower response as compared to TCA [Table - 3].

The response was inversely proportional to the duration of disease. With chronic pigmentation there was lesser improvement. In patients with chronic pigmentation i.e. 1-3 year, response with TCA was more (31.3% had> 50% improvement) where as GA was more effective when duration of onset was < 1 year (27.9% had> 50% improvement) comparative assessment is shown [Table - 4]. TCA patients experienced more local irritant effects like tingling, burning sensation and post peel crackening as compared to GA.

After a follow up period of 3 months overall relapse was seen in 8% and hyperpigmentation in 4% patients. Important observation is that relapse and hyperpigmentation were 25% with TCA as compared to 5.9% only in GA.

Discussion

The preponderance of younger female patients in our study conforms to previous studies and shows that melasma is more cosmetically disturbing for them and they form the major group demanding treatment.[1]

Wood′s light examination was not used because most of our patients were of skin type III to V and hence differentiation of the depth of pigmentation in our patients was not perceptible. Lawrence, et al have shown that Wood′s light did not help in assessing the response to treatment.[14]

Sun exposure being the most important precipitating factor can be explained because of the more intense and prolonged sunshine seen in this arid region - Jodhpur the ′Sun city′ of our country.

The results showed that more than half of the patients had greater than 50% improvement. Response with TCA was rapid but was unpredictable, associated with local reactions and significant relapse rate whereas response with GA was slower in onset, not associated with local irritant reactions and was more prolonged. These features make GA in comparison to TCA a better peeling agent in melasma.

The study proposes to combine these modalities whereby TCA can be used initially to get a prompt relief and then followed by GA to further reduce the pigmentation, maintatin the effect and prevent relapse. Follow up period in our study was too short to make definite conclusions. All these findings pave the way for more elaborate studies at other centres with larger number of patients and a long follow up keeeping these considerations into account.