Pathology/Lab Coding Alert

Question: We have a dermatology client who, when performing a Mohs procedure, sometimes asks our pathologist for additional studies such as biopsies, special stains, or pathology review of a tissue specimen. Occasionally, this work doesn’t get paid. What are some strategies for us to avoid denials?

South Dakota Subscriber

Answer: Mohs micrographic surgery is an unusual procedure that requires the physician to act as both the surgeon and the pathologist for neoplastic skin lesions. The intent is for the physician to remove as little tissue as possible, perform a histologic exam and margin evaluation in real time, and proceed to excise more tissue (perform an additional stage) until the entire lesion is excised. CPT^® provides 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) (eg, hematoxylin and eosin, toluidine blue), …) for the procedure, depending on the site and number of stages.

You’ll also encounter CPT^® guidance limiting how you can report additional pathology services with Mohs codes, and that might be the reason your pathologist is getting denials. Look at the following restrictions and how to override them when your pathologist performs additional medically necessary services.

Pathology exam: A CPT^® note states, “Do not report 88302-88309 on the same specimen as part of the Mohs surgery,” and a National Correct Coding Initiative (NCCI) edit enforces that rule by bundling the codes. However, if the pathologist performs a skin biopsy that diagnoses cancer and leads to a Mohs procedure on the same date, you can report 88304 (Level IVskin - Surgical pathology, gross and microscopic examination … skin, other than cyst/tag/debridement/plastic repair …), but you’ll need to override the Mohs edit using modifier 59 (Distinct procedural service).

Frozen section: If the dermatologist doesn’t have a cancer diagnosis on the date of surgery, instead of an 88304 service, it’s more likely that the pathologist will perform an intraoperative frozen section exam to provide the diagnosis. In that case, you would report 88331 (Pathology consultation during surgery; first tissue block, with frozen section(s), single specimen) on the same date as the Mohs service. Again, an NCCI edit could derail your pathologist’s pay unless you report the service with a modifier such as 59.

Special stain: The Mohs procedure includes routine stains such as hematoxylin and eosin (H&E) as mentioned in the code descriptor. But the dermatologist might request that your pathologist perform a non-routine stain on a frozen section during the Mohs, such as an immunohistochemistry (IHC) stain. In that case, you should list +88314 (Special stain including interpretation and report; histochemical stain on frozen tissue block (List separately in addition to code for primary procedure)). Based on an NCCI edit for the special stain with Mohs, you’ll need modifier 59 in this case, too.

Review: The physician may request a diagnostic review of a tissue specimen, and with the proper written request and reporting, the procedure could qualify for a pathology consultation. You should report that service with an appropriate code such as 88321 or 88323 (Consultation and report on referred … [slides or material]). You won’t need a modifier to list this code in addition to a Mohs procedure.