Dermatology Coding Alert

Question: If the physician in our practice performs Mohs on four different lesions, should I code for stage one, two, etc., for each lesion? The physician in our practice thinks that coding 17304 x 4, 17305 x 4, etc., is correct, but I'm not clear on what is correct.

Nebraska Subscriber

Answer: Based on the description you provide, your physician is correct in coding the excision of four lesions: 17304 (Chemosurgery [Mohs micrographic technique], including removal of all gross tumor, surgical excision of tissue specimens, mapping, color coding of specimens, microscopic examination of specimens by the surgeon, and complete histopathologic preparation including the first routine stain [e.g., hematoxylin and eosin, toluidine blue]; first stage, fresh tissue technique, up to 5 specimens) x 4, then re-excising them (17305, ... second stage, fixed or fresh tissue, up to 5 specimens) x 4, and so on up to +17310 (... each additional specimen, after the first 5 specimens, fixed or fresh tissue, any stage [list separately in addition to code for primary procedure]) depending on how many stages the physician completed to remove all abnormal or malignant tissue from the lesion site.

The process of Mohs surgery is complicated and includes multiple stages. When a patient presents to your physician for excision of malignant lesions, the physician performs pathology services in addition to excising the lesion when she completes a microscopic examination of the excised tissue.
 
For instance, a patient presents with a malignant lesion on his ear.

First stage: The physician excises the lesion, plus margins, and examines the tissue. Then the physician examines the lesion under a microscope and finds malignant cells in the margins.  

Second stage: Based on these findings, the physician excises more tissue from the area where she excised the original lesion and examines the additional specimen under the microscope.
 
The physician continues to excise the margins of the original lesion site until she does not find any other malignant or abnormal cells during microscopic examination.