Mohs Micrographic Surgery for Clear Coding

Location, quantity, and a physician doing two jobs are key to this procedure.

By Susan Ward, CPC, CPC-H, CPC-I, CDERC, CEMC, CPRC

Mohs micrographic surgery is a highly-effective technique for treating skin cancer, which commonly includes basal cell carcinoma and squamous cell carcinoma. Mohs micrographic surgery is used less often for patient with melanoma, which requires permanent pathology rather than frozen sections. The procedure is usually done in an outpatient setting, and typically involves several stages.

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The physician begins the first stage by removing the lesion. This specimen is divided into smaller portions, called blocks. The block’s location within each stage is carefully mapped, and each block is examined for cancer cells. The same physician acts as both the surgeon (excising the tissue) and the pathologist (examining each block’s slides).

If cancerous cells are found in any portion (block) within the specimen (stage), the physician will excise additional tissue from the mapped area containing the cancerous cells. This is the second stage, which further divides the blocks for examination. The process is repeated until no cancer evidence remains. With this process, the physician can excise the entire cancer while sparing as much of the surrounding tissue as possible.

Location is First Code Selection Factor

CPT® categorizes Mohs micrographic surgery procedures by location, with one code set for head, neck, hands, feet, and genitalia, and a second code set for trunk, arms, and legs. Both anatomic categories include an add-on code for each additional stage after the first, with a stage defined as including up to five tissue blocks:

 

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

+17312                  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; each additional stage after the first stage, up to 5 tissue blocks (list separately in addition to code for primary procedure)

Report add-on code 17312 in addition to 17311, only.

17313                  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), of the trunk, arms or legs; first stage, up to 5 tissue blocks

+17314                  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), of the trunk, arms or legs; each additional stage after the first stage, up to 5 tissue blocks (list separately in addition to code for primary procedure)

Claim 17314 as an add-on code only with 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), each additional block after the first 5 tissue blocks, any stage (list separately in addition to code for primary procedure)

You may apply 17315, when appropriate, in addition to any codes in the 17311-17314 range.

Quantity is Second Code Selection Factor

To select the correct Mohs micrographic surgery codes, you should know—in addition to location—how many stages of each lesion the physician excised, and how many blocks the physician divided each stage into.

For example, a patient has a squamous cell carcinoma on the tip of the nose. After prepping the patient and site, the physician removes the carcinoma (first stage) and divides it into eight blocks for examination. Seeing positive margins, he removes a second stage, which he divides into five blocks. The physician again identifies positive margins. He performs a third stage and divides the specimen into three blocks proving to be clear of carcinoma. The appropriate coding in relative value unit (RVU) order is:

17311—(first stage)

17312 x 2—(second and third stage)

17315 x 3—(blocks, six, seven, and eight from the first stage)

Diagnosis: 173.3 Malignant carcinoma of skin, other and unspecified parts of face

If the physician performs Mohs micrographic surgery on four separate lesion sites, you should apply the Mohs micrographic surgery codes once per lesion. For example, if the physician performs stage one on four leg sites, report four units of 17313; for stage two on the same four sites, report four units of 17314; and so on.

In the majority of circumstances, you would not list a pathology exam code in addition to the Mohs micrographic surgery code for the same service. CPT® guidelines specify, “Do not report 88302-88309 on the same specimen as part of the Mohs surgery.” The National Correct Coding Initiative (CCI) bundles 17311 and 17313 with surgical pathology codes 88302-88309 and 88300 Surgical pathology, gross examination only.

Review Exceptions and Special Cases

An exception to this rule may occur if a pathologist had performed a biopsy with a confirmed cancer diagnosis, which results in a same-day Mohs micrographic surgery procedure. The AMA’s CPT® Assistant (July 2004) advises the physician may need a new biopsy before performing Mohs micrographic surgery if:

  • A biopsy report is not available with reasonable efforts
  • A biopsy has been done more than 90 days before surgery
  • The original biopsy is ambiguous

If the Mohs micrographic surgery proceeds on the same day based on the biopsy diagnosis, append modifier 59 Distinct procedural service to the pathology code (such as 88305 Level IV—Surgical pathology, gross and microscopic examination). Modifier 59 indicates the biopsy is not a Mohs surgery component, but is a separate, distinct service.

When the physician uses stains such as hematoxylin and eosin (H&E), you cannot claim the surgical pathology special stain codes in addition to the Mohs micrographic surgery codes. The Mohs micrographic surgery definition states the procedure includes routine stains, such as H&E or toluidine blue.

If the physician performs another stain not typically part of Mohs tissue processing, you can, however, use the appropriate special stain code with modifier 59 in addition to the Mohs micrographic surgery code(s). CPT® instructions preceding 17311 and following 88314 Special stains (List separately in addition to code for primary service); histochemical staining with frozen section(s) instruct, “When a nonroutine histochemical stain on frozen tissue is utilized, report 88314 with modifier 59.” For example, the physician might examine an Oil Red O lipid stain on frozen sections, which warrants reporting 88314-59 in addition to the Mohs micrographic surgery codes.

Apply 17311-17315 only if the physician excises the tissue and also examines the excised tissue to locate remaining suspicious cells. Mohs micrographic surgery “requires a single physician to act in two integrated but separate and distinct capacities: surgeon and pathologist,” according to CPT®.

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

This case 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 (88331 Pathology consultation during surgery; first tissue block, with frozen section[s], single specimen and 88332 Pathology consultation during surgery; 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).

Remember to refer to your neoplasm table for the most appropriate diagnosis for the patient’s skin cancer.

Repairs Are Separate With Mohs

Regardless of whether the reconstructive surgeon is the same person who performed the Mohs micrographic surgery or a different person, he can bill separate reconstruction codes for flaps or grafts, according to CPT® instructions.

For example, following Mohs micrographic surgery, a surgeon uses two advancement flaps to repair a 2.4 cm excision. Although he uses two flaps, there is only one defect site and only one applicable code, 14060 Adjacent tissue transfer or rearrangement, eyelids, nose, ears, and/or lips; defect 10 sq cm or less.

Note: Receiving repair procedure payment may be a challenge because some insurers may classify a closure following a multi-step excision as cosmetic. To make your case for medical necessity, be sure to link the cancer diagnosis to your reconstruction code. For instance, you would use 140.1 Malignant neoplasm of lip; lower lip, vermilion border to report the squamous cell carcinoma. With such a diagnosis, you may consider submitting photographic defect evidence to the carrier to further support the reconstructive nature rather than cosmetic nature of the surgery.

Susan Ward,
CPC, CPC-H, CPC-I, CDERC, CEMC, CPRC

Susan Ward, CPC, CPC-H, CPC-I, CDERC, CEMC, CPRC, has 20 years coding and billing experience. She currently works for a reconstructive plastic surgeon in Phoenix, Ariz. She is an approved Professional Medical Coding Curriculum (PMCC) instructor, AAPC workshop presenter, past president of her local AAPC chapter, and a 2007-2009 AAPC National Advisory Board (NAB) member.

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One Response to “Mohs Micrographic Surgery for Clear Coding”

  1. Amy Krahl, PA says:

    Ms. Ward,

    I am a dermatology PA seeking detailed info on PAs ability to bill separately for Mohs closures in an outpatient setting. I don’t want to take your time but I would greatly appreciate any direction you could point me.

    Thank you,

    Amy

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