Definition of Mohs Micrographic Surgery CPT code

Mohs micrographic surgery is a special technique used to treat complex or ill-defined skin cancer and requires a single physician to provide two distinct services. The first service is surgical and involves the destruction of the lesion by a combination of chemosurgery
and excision. The second service is that of a pathologist and includes mapping, color coding of specimens, microscopic examination of specimens, and complete histopathologic preparation. This work requires a specially trained physician acting as both surgeon and pathologist. CPT code 17311, +17312, 17313, +17314 & +17315 are used to report  Mohs micrographic surgery.

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Description of Mohs micrographic surgery CPT code 17311, +17312, 17313, +17314 & +17315

The physician performs chemosurgery using Mohs micrographic technique. The physician places a chemical agent on the lesion prior to excision. This chemical acts as a tissue fixative. The lesion is excised via serial tangential cuts, allowing the physician to more closely assess wound margins and the extent of the defect being excised.

CPT code 17311 is reported for first stage, fresh tissue, up to five specimens of the head, neck, hands, feet, genitalia, or any location with surgery directly involving muscle, cartilage, bone, tendon, major nerves, or vessels and CPT code 17312 for each additional stage, fixed or fresh tissue, up to five specimens. CPT code 17313 is reported for first stage, fixed or fresh tissue, up to five specimens of the trunk, arms, or legs and CPT code 17314 for additional stages, each stage, up to five specimens. CPT code 17315 is reported in addition to the code for the primary procedure for each additional block after the first 5 tissue blocks, any stage.

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

+17312 each additional stage after the first stage, up to 5 tissue blocks

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) (e.g., hematoxylin and eosin, toluidine blue), of the trunk, arms, or legs; first stage, up to 5 tissue blocks

+17314 each additional stage after the first stage, up to 5 tissue blocks

+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), each additional block after the first 5 tissue blocks, any stage

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Coding Example for Mohs micrographic surgery CPT codes

A patient has a biopsy-proven basal cell carcinoma on his forehead measuring approximately 1 cm in diameter. The surgeon administers local anesthesia, excises the visually evident tumor and then removes an additional horizontal layer of tissue. This slice of tissue is color-coded and mapped, cut into seven specimens and prepared into slides for pathological examination. The surgeon reviews the slides and the margins are found to have malignant cells so the patient is prepped again. (STAGE 1)
CPT Code: 17311

The surgeon removes another horizontal layer of tissue from three-quarters of the wound bed. This slice of tissue is color-coded and mapped, cut into four specimens and prepared into slides. The surgeon examines the slides and finds more malignant cells so the patient is prepped again. (STAGE 2)
CPT Code: 17312

The surgeon removes another horizontal layer of tissue from half of the wound bed. This slice of tissue is color-coded and mapped, cut into three specimens and prepared into slides. The surgeon examines the slides and finds more malignant cells so the patient is prepped again. (STAGE 3)
CPT Code: 17312

The surgeon removes another horizontal layer of tissue from one quarter of the wound bed. This slice of tissue is color-coded and mapped, cut into two specimens and prepared into slides. The surgeon examines the slides and the margins are clear of malignant
cells. The patient is prepped for wound closure. (STAGE 4)
CPT Code: 17312

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Question

A patient with a 1.2 x 0.6 cm squamous cell carcinoma of the right temple presented for Mohs micrographic surgery. At the initial stage, the tumor was debulked/excised along with the peripheral and deep margins. The tissue was mapped and color-coded. The microscopic examination revealed tumor persisting in the deep portion of the specimen; therefore, the patient required additional Mohs stages. In the final stage, stage IV, the surgeon’s microscopic examination of the specimen revealed no additional tumor however, due to perineural inflammation and concern for perineural tumor invasion, the surgeon melted down the tissue block and sent it for special stains to an outside facility. The final defect measured 2.5 x 2.1 cm and the patient was referred to plastic surgery for closure.

Given Mohs codes may only be reported when the physician operates as both surgeon and pathologist, does sending tissue for special stains (after the surgeon has reviewed) negate the option for reporting codes from the Mohs surgery code range 17311-17315? What are the appropriate CPT codes the facility should report for this case?

Answer

Assign CPT code 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, for the first Mohs stage.

Report three units of CPT code 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), for stages 2-4.

Since sending the tissue block out for special stains was in addition to, not instead of, performing the elements of Mohs surgery, it does not negate the reporting of the Mohs surgery codes. The Mohs Micrographic Surgery section of the CPT codebook states that nonroutine stains should be separately reported with code 88314. However, that code should not be reported in this case because the special stains were performed at a different facility.