Pathology/Lab Coding Alert

Question: Our dermatopathologist removed a squamous cell carcinoma from the patient’s nose and processed it in three blocks, examined the tissue, and found the margins were not clear. The dermatopathologist proceeded to perform a second excision to remove the positive margin, which he processed as one block, finding margins clear. How should we report the procedure(s) and diagnosis?

Oregon Subscriber

Answer: The correct coding for the procedures you describe is 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] [e.g., 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) and +17312 (… each additional stage after the first stage, up to 5 tissue blocks [List separately in addition to code for primary procedure]).

This is Mohs micrographic surgery procedure in which a single physician functions both as the dermatologist and pathologist. It’s a two-stage procedure, because the physician excises and evaluates a lesion (stage 1), but finding that the margins were not clear, the physician then performs an additional excision and pathology evaluation (stage 2).

Notice blocks: For both codes 17311 and +17312, a single unit describes the work for up to five tissue blocks. If the dermatopathologist excises a large lesion that requires more than five blocks, you would report +17315 (…each additional block after the first 5 tissue blocks, any stage [List separately in addition to code for primary procedure]) for each additional block beyond five blocks in a particular stage.

Check out diagnosis: The appropriate diagnosis code for this case is C44.321 (Squamous cell carcinoma of skin of nose).