How effective is 30% versus 100% TCA CROSS for acne scars? (photo)

Thank you for your question. TCA CROSS (trichloroacetic acid chemical reconstruction of skin scars) is a good technique for atrophic acne scars, especially of the ice pick morphology, but there is some variation in technique among doctors as each doctor has their own preferred way of performing it.

How effective is 30% TCA CROSS versus 100% TCA CROSS for acne scars?

100% TCA CROSS has been shown to be effective in multiple published studies. Excellent results (>70% improvement) are seen in the large majority (>70%) of patients. With adequate precautions (such as UV avoidance, sunblock, topical medications like hydroquinone, tretinoin) before and after, 100% TCA CROSS has minimal complications even in dark skin types.

Personally, I feel that 30% TCA is too low a concentration for effective TCA CROSS as it would only penetrate into the superficial dermis. The lowest concentration of TCA I have come across for the CROSS technique in published studies is 50%. Interesting, the study showed that 50% TCA had similar results to 90%.

I use a syringe technique (I find this faster, more precise and controlled) starting with 70% or 80% TCA and gradually work up to 100% TCA. If the risk of post-inflammatory hyperpigmentation (PIH) is a concern, we can do a test spot on one of the scars. In my experience, however, PIH has not been a problem if the patient is diligent with pre and post-procedural care. Pain-wise, so far patients' have fed back that TCA CROSS is quite bearable even with 100% TCA.

From the provided images, I would suggest TCA CROSS combined with fractional microneedling radiofrequency. It's not very clear whether you have any rolling or tethered scars which would benefit from subcision and filler, this needs to be assessed in person.

Do consult a doctor who will be able to give you detailed advice for your scars.

Hope this helps!

Warmest regards,

Dr Wan Chee Kwang

References
1. Khunger et al. Evaluation of CROSS technique with 100% TCA in the management of ice pick acne scars in darker skin types. J Cosmet Dermatol. 2011 Mar;10(1):51-7.

2. Cho et al. Histometric and Histochemical Analysis of the Effect of Trichloroacetic Acid Concentration in the Chemical Reconstruction of Skin Scars Method. Dermatol Surg 2006;32:1231–1236

3. Fabbrocini et al. CROSS technique: chemical reconstruction of skin scars method. Dermatol Ther. 2008 Nov-Dec;21 Suppl 3:S29-32.

4. Whang et al. Letter: Chemical Reconstruction of Skin Scars (CROSS) Method Using a Syringe Technique. Dermatol Surg 2007;33:1539–1540

Thank you for your question and photo. From your photo, I agree you will be an excellent candidate for TCA CROSS followed by Fractional CO2 laser resurfacing for optimal improvement of your acne scars. Whether you use 30% or 100% TCA CROSS refers to the strength of the trichloroacetic acid (TCA) applied to the scars. 100% TCA will give a better result than 30% but increase the risk of post inflammatory hyperpigmentation ie the brown marks that may appear after the initial scabs fall off.

For Chinese patients, I tend to use 70% TCA, as I believe it gives good results without causing too much post inflammatory hyperpigmentation. For darker skinned individuals, one may consider a lower strength of TCA, so that they do not get too much brown darkening after. The pain during application is actually very bearable, with most patients experiencing slight stinging sensation and redness, even when TCA 70% is used.

Hope this is helpful.

Warmest regards

Dr Stephanie Ho, Dermatologist

Personally I have never performed TCA CROSS at a 30% concentration because it is too low a concentration to produce results (if any). A 80% concentration for your case would be a good starting point.

Subsequently, skin resurfacing treatments such as the Fractional CO2 laser (if necessary) would be ideal to achieve further improvement and smoothening of the scars.

Hope that helps.

All the best!