Oncology & Hematology Coding Alert

Question: A patient presented to our physician with a diagnosis of primary squamous cell carcinoma on the vermilion border of his lower lip. Our physician planned an excision of the lesion. To preserve the integrity of the healthy skin surrounding the neoplasm, the excision was done in layers.  

Our practice doesn’t have the clinical pathology equipment necessary to biopsy each excised layer, but we have arrangements with a nearby hospital that will provide the pathology needed. After our physician removed tissue, the 1.8 cm excision was taken to the hospital where pathology examined the section. The physician had to wait three days for the pathology report notifying her that the tissue sample was malignant.

During the follow-up session, our physician proceeded with two more stages of lesion excision (comprising margins of 2.1 cm and 2.4 cm). It wasn’t until the 2.4 cm excision that the hospital’s pathologist was able to report no sign of cancer. Can we report Mohs codes and what modifier do we need to add?

Texas Subscriber

Answer: Even though your physician removed the malignant lesion layer-by-layer, you cannot report this work using Mohs chemosurgery codes, 17311 (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 histopathologic preparation including routine stain[s] [eg., hematoxylin and eosin, toluidine blue], head, neck, hands, feet, genitalia, or any location with surgery directly involving muscle, cartilage, bone, tendon, major nerves, or vessels; first stage, up to 5 tissue blocks) through +17315 (……each additional block after the first 5 tissue blocks, any stage [List separately in addition to code for primary procedure]).

To report Mohs, the physician needs to work as both an oncologist and a pathologist. In this case, the pathological analysis was outsourced to a hospital.

Report the first 1.8 cm excision with 11642 (Excision, malignant lesion including margins, face, ears, eyelids, nose, lips; excised diameter 1.1 to 2.0 cm) and 11643 (... excised diameter 2.1 to 3.0 cm) for the 2.4 cm excision. Be sure to alert the provider of the importance of documenting the surgical plan in each procedure note. More specifically, a notation that potential additional excisions would be performed within a short period if the pathology results were adverse. When documented properly, you may attach modifier 58 (Staged or related procedure or service by the same physician or other qualified health care professional during the postoperative period) to 11643.

Medicare views same-operative-session excisions and re-excisions as one procedure so if the re-excision had occurred during the same operative session, you would not use modifier 58.