Our doctor did an excision of lesions on a patient & he also did a biopsy of a lesion on the right & the left leg. The CPT we used was 11100, 11101 & 11400-59. Medicare only paid 11101 & 11400-59 but did not pay on 11000 saying "not covered when performed during the same session/date as a previously processed service for the patient". What was wrong with it? there were two different lesions, different site, that's why we used 11100 for the first lesion & 11101 (add=on code) for the second lesion. I know we are not supposed to use modifier on 11101 because it is an add-on code. Do I need to appeal this with a modifier? Any help/suggestion will be greatly appreciated? Thank you