Answer: First, check the pathology report from the original biopsy and make sure it states “dysplastic nevus.” If the biopsy showed a dysplastic lesion, then the diagnosis is benign, and you should report the diagnosis as 238.2 (Neoplasm of uncertain behavior of skin).
With that diagnosis, you should code the re-excision using a code from the series 11400-11446 (Excision, benign lesion ...) based on lesion’s site and size.
Important: If you have a previous malignant lesion diagnosis and the surgeon performs a re-excision because there was a concern about clear margins from the first excision, use the original diagnosis code and the same family of lesion excision codes, even if the pathology subsequently comes back as benign.