Predicting the outcome of laser treatment for pigmented lesions.

Laser treatment of pigmented lesions requires melanocytes to lie within the range of penetration of the laser, and to contain melanin in order to absorb and covert light energy into heat by photothermolysis. This study investigated whether these limitations could be tested by immunohistology and used to predict the outcome of treatment. Punch biopsies were taken from 32 patients prior to laser treatment. Immunohistology targeting the S-100 antigen allowed measurement of melanocytic depth and the presence of amelanosis. These parameters provided an accurate method of predicting good results (sensitivity 81%, specificity 93%) and were particularly useful in delineating the likelihood of a poor/very poor outcome (sensitivity 100%), even beyond the predictive capacity of the test patch. No complications were associated with the biopsy technique which reliably provided sufficient material for histological assessment. This study reports the clinical applications of this test to laser treatment.