Question: A patient of one of our dermatologists presented with a diagnosis of primary squamous cell carcinoma on the vermilion border of his lower lip. To preserve the integrity of the healthy skin surrounding the neoplasm, the dermatologist decided to excise the lesion 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 dermatologist removed tissue, the 1.8 cm excision was taken to the hospital where pathology froze and examined the section. The dermatologist had to wait three days for the pathology report notifying her that the tissue sample was malignant.
During the follow-up session, the dermatologist 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. Our dermatologist then repaired the 2.4 cm defect using two advancement flaps.
Can I report Mohs codes and what modifier do I need to add?
Texas Subscriber
Answer: Even though the dermatologist removed the malignant lesion layer-by-layer, you cannot report her work using Mohs chemosurgery codes (17311-17315, 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] [e.g., hematoxylin and eosin, toluidine blue] …).
To report Mohs, the physician needs to work as both a surgeon and a pathologist. In this case, the pathological analysis was outsourced to a hospital.
You should 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 2.1 cm excision. 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 be able to use modifier 58.