Pathology/Lab Coding Alert

Number of physicians should determine your code choice

A pathologist diagnoses a cancerous skin lesion removed by a dermatologist and reports the need for further excision during the same surgical session. If you would code this procedure as Mohs surgery, you're putting your physicians at risk for fraud charges.

Know where to draw the line: Mohs surgery is one of the most effective treatments for skin cancer. But successful coding requires knowing when you must use different surgery and pathology codes, when you're allowed to use Mohs codes, and how to report each stage when Mohs codes are appropriate. Let the answers to these frequently asked questions guide you to ethical Mohs coding.

Just One Physician Performs Mohs

Q: When should I use the Mohs codes?

A: The Mohs chemosurgery codes (17304-17310, 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]...) are unique because they are "the only CPT codes that describe procedures that involve surgery and pathology services performed together by the same surgeon or pathologist," the July 2004 CPT Assistant states.

In Mohs surgery, "the physician works as a surgeon and a pathologist," says Margarida Cabral, CPC, coder for the Lahey Clinic in Burlington, Mass. Report these codes only if the physician both excises the tissue and examines the excised tissue to locate remaining tumors, she says. If a dermatologist excises the tissue and a pathologist examines it, you should report their services with entirely different codes.

Example: A dermatologist removes a skin lesion 0.8 cm in diameter and sends the specimen to a pathologist for a consultation during surgery. The pathologist fresh-freezes the tissue, processing it in two tissue blocks, and examines the margins microscopically, marking the location of any remaining tumor on the surgical wound map. The pathologist later examines permanent sections to provide a definitive diagnosis.

This case does not involve a Mohs procedure. Rather, it involves a dermatologist's surgical service (11641, Excision, malignant lesion including margins, face, ears, eyelids, nose, lips; excised diameter 0.6 to 1.0 cm) and a pathologist's consultation service: ICD9 88331 (Pathology consultation during surgery; first tissue block, with frozen section[s], single specimen) and 88332 for the second block (... each additional tissue block with frozen section[s]). The pathologist also performs a surgical pathology service: 88305 (Level IV--Surgical pathology, gross and microscopic examination, skin, other than cyst/tag/debridement/plastic repair).

Lesson learned: Don't use Mohs codes if two separate physicians perform the skin excision and examination. Use surgical codes when a dermatologist excises a skin lesion and separate pathology codes when a pathologist examines the tissue.

Never list a pathology exam code in addition to the surgical Mohs code for the same service.

Stages and Blocks are Coding Keys

Q: If the pathologist or dermatologist performs both steps--surgery and intraoperative pathology exam--how should I use the Mohs codes?

A: To pick the correct Mohs surgery codes, you need to know two things:

• how many layers (stages) of each lesion margin the physician excised

• how many pieces (tissue blocks) the physician divided each layer into.

For the first layer (stage), up to five blocks, report 17304 (... first stage, fresh tissue technique, up to 5 specimens).

If the physician excises three stages of the lesion, in addition to 17304, you would report 17305 (... second stage, fixed or fresh tissue, up to 5 specimens) and 17306 (... third stage, fixed or fresh tissue, up to 5 specimens). For stages beyond the third stage, report one unit of 17307 (... additional stage[s], up to 5 specimens, each stage) for each stage.

Large specimen means more codes: Note that each CPT code definition specifies "up to 5 specimens." If the excised lesion is especially large, however, the pathologist/surgeon may need to divide the tissue into more than five blocks. In that case, you would report +17310 (... each additional specimen, after the first 5 specimens, fixed or fresh tissue, any stage [list separately in addition to code for primary procedure]) once for each specimen after the fifth, in addition to the code that corresponds to that stage, says April Blueher, CPC, coder for the Shideler Dermatology Group in Carmel, Ind.

Example: The physician excises a total of five stages. In the first stage, he needs to divide the tissue into seven specimens (blocks). You would code:

• One unit of 17304 (first stage)
• One unit of 17305 (second stage)
• One unit of 17306 (third stage)
• Two units of 17307 (fourth and fifth stages)
• Two units of 17310 (sixth and seventh specimens of the first stage).

Start Over for Each Lesion

Q: The physician performs Mohs on four separate lesion sites. How should I code?

A: Use the Mohs codes once per lesion. If the physician performs stage one on four sites, report four units of 17304; for stage two on four sites, report four units of 17305; and so on.

Biopsy Stands Alone

Q: If the pathologist examines a biopsy that results in a cancer diagnosis and later the same day performs a Mohs surgery, can I report the biopsy separately?

A: Yes, if it's medically necessary. The physician must have a histologic diagnosis from a skin biopsy before beginning Mohs.

If a diagnosis isn't available, he must perform a biopsy to definitively diagnose the skin cancer. CPT Assistant (July 2004) says that the physician may need a biopsy before performing Mohs if:

• a biopsy report is not available with reasonable effort

• a biopsy has been done more than 90 days before surgery

• the original biopsy is ambiguous.

If the pathologist performs an intraoperative frozen tissue exam, report 88331. Code the pathologist's permanent-section biopsy exam using 88305. For the surgical skin removal for biopsy, the surgeon would use codes 11100-11101 (Biopsy of skin ...).

Same day? Use 59: If the Mohs surgery proceeds on the same day based on the diagnosis, append modifier 59 (Distinct procedural service) to the biopsy and pathology codes to indicate that they are not components of the Mohs surgery, July 2004 CPT Assistant says.

Mohs Includes Stain

Q: When the pathologist uses stains such as H&E, can I use the surgical pathology special stain codes in addition to the Mohs codes?

A: No. The Mohs definition states that the procedure includes "the first routine stain," such as hematoxylin and eosin (H&E) or toluidine blue. National Correct Coding Initiative edits bundle the Mohs codes 17304-17310 with special-stain codes +88313 (Special stains [list separately in addition to code for primary service]; Group II, all other [e.g., iron, trichrome], except immunocytochemistry and immunoperoxidase stains, each) and +88314 (... histochemical staining with frozen section[s]).