Don’t Marginalize Mohs 

Don’t Marginalize Mohs 

Examine the documentation for better coding.

Co-written by Susan Ward, CPC, COC, CPC-I, CEMC, CPCD, CPRC

When reporting Mohs surgery for treatment of skin cancer, documentation must confirm that a single provider acted as both the surgeon (excising tissue) and pathologist (immediately examining excised tissue to determine clear margins). “If either of these responsibilities is delegated to another physician or qualified healthcare professional who reports the services separately the … [Mohs] codes should not be reported,” according to CPT® requirements.

Select Initial Code by Location

CPT® assigns Mohs codes by location. For lesions of the head, neck, hands, feet, and genitalia — or any location with surgery directly involving muscle, cartilage, bone, tendon, major nerves, or vessels — report 17311 and +17312. For lesions of the trunk, arms, and legs, select 17313 and +17314 (see sidebar “Mohs Code Descriptions” for code descriptions).

Codes 17311-17314 include up to five tissue blocks. If a single stage must be divided into more than five blocks, report an add-on code for each additional block beyond the initial five using +17315.

Stage Equals Excision, Block Equals Examination

To spare as much healthy tissue as possible, the physician removes tissue in stages and begins by excising the lesion. This is the first stage. The specimen is divided into smaller portions, called blocks. The locations of each block within this stage are carefully mapped, and each block is examined for cancer cells.

If the surgeon sees a clear margin (no malignant tissue), no further excision is necessary beyond that block. If the physician finds malignancy, a further stage is necessary to remove additional tissue. This is the second stage, which is again divided into blocks. The process repeats, adding stages divided into blocks, until no cancer cells remain.

In other words, each time the surgeon excises tissue is a stage. Each slide resulting from an individual stage is a block.

For example, a patient presents with a basal cell carcinoma (BCC) of the nasal tip measuring 7 mm. The surgeon excises the tissue and cuts the specimen into six blocks. On examination of the tissue blocks, the surgeon finds positive margins on two of the blocks. The surgeon then excises an additional specimen (stage) and divides that specimen into two blocks. On examination, the specimens are clear of malignancy.

Report 17311 for the first stage, +17312 for the second stage, and +17315 for the additional block.

Separately Consider Each Lesion Treated 

If the surgeon/pathologist uses the Mohs technique on multiple lesions during the same session, code each lesion, separately.

For example, the patient presents with a BCC on her left cheek measuring 5 mm, and an squamous cell carcinoma (SCC) of her chin measuring 4 mm. The surgeon first excises the BCC of the left cheek, cutting the specimen into three blocks with clear margins. Next, the surgeon excises the SCC of the chin and examines the specimen in one block with clear margins.

Report 17311, 17311-59 Distinct procedural service (to indicate the separate excision). Don’t forget to append diagnostic codes, accordingly.

Mohs Code Descriptions

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)

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)

+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)

Don’t Miss Out on Separate Services with Mohs

When billing for Mohs, many common services are included, but there are exceptions.

For example, typically you would not report biopsy separately with Mohs. The exception occurs when there is no prior pathology confirmation of a diagnosis. In that case, the same-day biopsy (11100 Biopsy of skin, subcutaneous tissue and/or mucous membrane (including simple closure), unless otherwise listed; single lesion, +11101 Biopsy of skin, subcutaneous tissue and/or mucous membrane (including simple closure), unless otherwise listed; each separate/additional lesion (List separately in addition to code for primary procedure)) and frozen section pathology (88331 Pathology consultation during surgery; first tissue block, with frozen section(s), single specimen) may be reported separately in addition to the Mohs surgery, CPT® instructs. Append modifier 59 Distinct procedural service to the biopsy and pathology codes to confirm that these procedures are not a routine part of the Mohs procedure.

An example would be if a patient is scheduled for a Mohs procedure for a malignancy on his forehead; and prior to the procedure, the surgeon identifies a suspicious lesion on the patient’s right nasal ala, for which the patient agrees to have a biopsy.

Mohs surgery includes “routine stains,” such as hematoxylin and eosin (H&E) or toluidine blue. If the physician performs an additional, atypical stain, report the appropriate special stain code. CPT® instructs, “When a non-routine histochemical stain on frozen tissue is utilized, report 88314 [Special stain including interpretation and report; histochemical stain on frozen tissue block (List separately in addition to code for primary procedure)] with modifier 59.”

Finally, CPT® tells us that if a repair is performed following Mohs, “use separate repair, flap, or graft codes.”

Histopathologic examination is included in the Mohs procedure. Do not separately report 88302-88309.


Susan Ward, CPC, COC, CPC-I, CEMC, CPCD, CPRC, has worked in the business side of medicine for over 25 years, and is a past member of the 2007-2009 NAB and the 2012-2015 AAPC Chapter Association. She is the revenue cycle analyst for a 638-IHS Facility in Arizona.

John Verhovshek

John Verhovshek

John Verhovshek, MA, CPC, is Managing Editor at AAPC. He has covered medical coding and billing, healthcare policy, and the business of medicine since 1999. He is an alumnus of York College of Pennsylvania and Clemson University, and a member of the Asheville-Hendersonville AAPC Local Chapter.
John Verhovshek

About Has 474 Posts

John Verhovshek, MA, CPC, is Managing Editor at AAPC. He has covered medical coding and billing, healthcare policy, and the business of medicine since 1999. He is an alumnus of York College of Pennsylvania and Clemson University, and a member of the Asheville-Hendersonville AAPC Local Chapter.

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