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Author: Dr Ian Logan, Dermatology Specialist Registrar, Hammersmith Hospital, London, United Kingdom. November 2015. Updated by Dr Ebtisam Elghblawi, Dermatologist, Tripoli, Libya. DermNet NZ Editor in Chief: A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. October 2018.
TCA CROSS is the chemical reconstruction of skin scars (CROSS) using trichloroacetic acid (TCA). It is most often used as an outpatient clinic procedure to treat atrophic acne scars. It's inexpensive, safe and efficient, but is not always effective.
The TCA CROSS procedure involves depositing small amounts of TCA at high concentration (70–100%) onto the surface of the atrophic scar. This causes a local inflammatory reaction leading to the formation of new collagen fibres. The aim is to improve the appearance of the scar by increasing collagen reflectance and reducing shadows cast over scar depressions. Complete resolution is unlikely to be achieved with this treatment method alone.
The decision to perform TCA CROSS depends on:
TCA CROSS is useful in the following types of atrophic scar:
Acne scar severity can be graded using Goodman and Baron’s qualitative acne scar grading system to allow objective pre and post-treatment comparisons.
Macular scars can be erythematous, hyperpigmented (brown) or hypopigmented (pale) flat marks. They do not represent a problem of contour like other scar grades but of colour.
Mild atrophic (thin) or hypertrophic (thick) scars may not be obvious at social distances of 50 cm or greater and may be covered adequately by makeup or the normal shadow of shaved beard hair in men or normal body hair if extrafacial.
Moderate atrophic or hypertrophic scarring is obvious at social distances of 50 cm or greater and is not covered easily by makeup or the normal shadow of shaved beard hair in men or body hair if extrafacial, but is still able to be flattened by manual stretching of the skin (if atrophic).
Severe atrophic or hypertrophic scarring is evident at social distances greater than 50 cm and is not covered easily by makeup or the normal shadow of shaved beard hair in men or body hair if extrafacial and is not able to be flattened by manual stretching of the skin.
TCA CROSS is technically straightforward to perform and can be undertaken in a matter of minutes, depending on the number of scars to be treated. It is generally repeated on several occasions at 2 to 4-week intervals.
Great care should be taken to avoid sensitive surfaces (eyes, mucosal surfaces). Eye covers may be used. Emergency eye irrigation equipment should be at hand. Avoid treatment of patients within 12 months of receiving systemic retinoid therapy due to the risk of healing complications.
The patient should be advised:
Most patients require 3 to 6 treatments with TCA CROSS for optimum improvement. Treatments may be repeated at 2 to 8 week intervals over 6 months.
TCA CROSS is generally well tolerated. Complications are rare when treatment is undertaken by an expert. They may include:
Treatments that can be combined with TCA CROSS for acne scars include:
Combination treatments may result in good outcomes with few complications.
When used correctly, TCA CROSS is moderately effective for atrophic acne scars. Patients may expect a 1 to 2-grade improvement in their acne scars over a 6-month period.
Greater levels of patient satisfaction are associated with more severe pre-treatment scarring.
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