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Mohs Micrographic Surgery - MMS (CPT codes 17311-17315) - Coding Guidelines


Mohs surgery, also known as chemosurgery, created by a general surgeon, Dr. Frederic E. Mohs, is performed to remove complex or ill-defined cutaneous malignancy.

CPT codes used to report Mohs micrographic surgery:

CPT Codes 17311 and 17313 are the base codes for the range of this surgery. CPT codes 17312, 17314 and 17315 are the add-on codes for this range.

CPT 17311: Moh’s micrographic technique, including removal of all gross tumor, surgical excision to 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.

CPT 17312 (Add-on code): Each additional stage after the first stage, up to 5 tissue blocks (List separately in addition to code for primary procedure)

CPT 17313 : Moh’s 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 stains(s) (eg. Hematoxylin and eosin, toluidine blue), of the trunk, arms, or legs; first stage, up to 5 tissue blocks

CPT 17314 (Add-on code): Each additional stage after the first stage, up to 5 tissue blocks (List separately in addition to code for primary procedure)

CPT 17315 (Add-on code): Moh’s 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 stains(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)

Coding Guidelines:

Report the appropriate Mohs surgery code for the body location surgery performed effected, with include any applicable surgery modifiers and the appropriate quantities for the specimens mapped in the days/units field.

Report CPT code 17312 for additional stages with first stage code 17311. Report CPT code 17314 for additional stages with first stage codes 17313. All the surgical procedure performed in the same operative session, including repairs should be reported on the same claim.

Do not report multiple instances of 17312 and 17314 on separate claim lines. These should be totaled and entered as a single item with appropriate units of service greater than one.

For each additional (separate) lesion treated with Mohs surgery on the same day, bill each first stage as a 17311 or 17313 as appropriate, on a separate claim line with a -59 modifier. Separately identify the additional stages for these lesions by billing the 17312 or 17314 on separate claim lines with a -59 modifier, and the appropriate units of service for these lesions.

CPT code 17315 may be used to report each block after the first 5 blocks for any single stage (17315 is used as an add-on code to 17311, 17312, 17313 or 17314). Please note that this code refers to the number of blocks, not number of slides.

If Mohs on a single site cannot be completed on the same day because the patient could not tolerate further surgery and the additional stages were competed the following day, you must start with the primary code (CPT code 17311) on day two. Computer edits will reject claims where a secondary code (e.g., CPT code 17312) is billed without the primary code (e.g., CPT code 17311) also appearing on same date of service, same claim.

Mohs Surgery and Surgical Pathology:

The use of CPT codes 17311-17315 is reserved for the surgeon who removes the lesion and prepares and interprets the pathology slides. The surgical pathology codes 88300-88309 and 88331-88332 and 88342 are part of the Mohs surgery and are bundled into 17311-17315. The surgeon should not append Modifier 59 to these pathology codes unless they pertain to a separate biopsy/excision that does not involve Mohs surgery.

Mohs Surgery and Skin Biopsy:

The Mohs micrographic surgery CPT codes include skin biopsy and excision services (CPT codes 11000-11001, 11600-11646, and 17260-17286).  However, if a suspected skin cancer is biopsied for pathologic diagnosis prior to proceeding to Mohs micrographic surgery, the biopsy (CPT codes 11000, 11001) and frozen section pathology (CPT code 88331) may be reported separately utilizing modifier 59 or 58 to distinguish the diagnostic biopsy from the definitive Mohs surgery.  Although the CPT Manual indicates that modifier 59 should be utilized, it is also acceptable to utilize modifier 58 to indicate that the diagnostic skin biopsy and Mohs micrographic surgery were staged or planned procedures.  Repairs, grafts, and flaps are separately reportable with the Mohs micrographic surgery CPT codes.

In order to allow separate payment for a biopsy and pathology on the same day as MMS, the -59 modifier is appropriate:
  • when the lesion for which Mohs surgery is planned has not been biopsied within the previous 60 days; or
  • when the surgeon cannot obtain a pathology report, with reasonable effort, from the referring physician; or
  • when the biopsy is performed on a lesion that is not associated with the Mohs surgery. 
Reimbursement:

Claims for Mohs surgery services are payable under Medicare Part B in the following places of service: office (11), inpatient hospital (21), outpatient hospital (22), ambulatory surgery center (24), independent clinic (49), federally qualified health center (50), state or local public health clinic (71) and rural health clinic (72).

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