Billing and Coding: Mohs Micrographic Surgery (MMS)

This Billing and Coding Article provides billing and coding guidance for Local
Coverage Determination (LCD) L33689 Mohs Micrographic Surgery (MMS). Please
refer to the LCD for reasonable and necessary requirements.  
  
Mohs Micrographic Surgery (MMS) is the technique for the removal of complex or
ill-defined skin cancer with histopathologic examination of 100% of the
surgical margins. MMS is a precise tissue-sparing, microscopically-controlled
surgical technique used in the removal and treatment of selected malignant
neoplasms of the skin. This surgery requires a single surgeon to act in two
distinct roles: surgeon and pathologist performing not only the excision but
also the histologic evaluation of the specimen(s). It is an approach that aims
to achieve the highest possible cure rates, and minimize wound size and
consequent distortions at critical sites such as the eyes, ears, nose, and
lips. MMS is a two-step process in which: (1) the tumor is removed in stages,
followed by immediate histologic evaluation of the margins of the specimen(s),
and (2) additional excision and evaluation is performed until all margins are
clear.  
  
Mohs surgery leaves an open wound, which most often is reconstructed (closed)
by the Mohs surgeon. Some wound management is included in the intra and post
service work of the Mohs surgery codes, and the Mohs surgeon has the option of
repair (closure) codes as appropriate.  
  
At this time, all laboratory tests covered under CLIA are edited at the CLIA
certificate level. The MMS procedure codes would require either a CLIA
certificate of registration (certificate type code 9), a CLIA certificate of
compliance (certificate type code 1), or a CLIA certificate of accreditation
(certificate type code 3). A facility without a valid current CLIA certificate
will not be permitted to bill for these procedures.  
  
 **Coding Guidance  
  
** ******Notice:** It is not appropriate to bill Medicare for services that
are not covered (as described by the entire LCD) as if they are covered. When
billing for non-covered services, use the appropriate modifier.  
  
Per the CPT codebook, if repair (closure) is performed, the Mohs surgeon may
report separate repair, adjacent tissue transfer or rearrangement, flap, or
graft codes. The guidelines at the beginning of applicable sections of the CPT
codebook define items that are necessary to report services and procedures.
Also, there are other instructions (such as parenthetical notes with selected
codes) that may restrict the use of certain additional procedure codes.
Physicians must code to specificity and code correctly. The National Correct
Coding Initiative edits applicable to certain procedures must not be
circumvented.  
  
A biopsy is necessary for the physician to determine the exact nature of the
lesion(s) to be removed. Occasionally, that biopsy may need to be done on the
same day that the Mohs surgery is performed because there was no prior
pathology confirmation of a diagnosis. In order to allow separate payment for
a biopsy and pathology on the same day as MMS, the -59 modifier or modifier
XU- unusual, non-overlapping service is appropriate when there is no biopsy of
the lesion for which Mohs surgery is performed within 60 days of the Mohs
surgery or when the biopsy is performed on a lesion that is not associated
with the Mohs surgery.  
  
If a pathology procedure is performed on the same day as the Mohs surgical
procedure, documentation must support a separate excision/biopsy/repair was
performed. Report diagnostic skin biopsy (11102 - 11107) and frozen section
pathology (88331) with modifier -59 or modifier XS-separate structure to
distinguish from the subsequent definitive surgical procedure of Mohs surgery.  
  
If additional special pathology procedures, stains, or immunostains are
required, use 88311-88314, 88341, 88342, and 88344.  
  
Do not report 88314 in conjunction with 17311-17315 for routine frozen section
stain (e.g., hematoxylin and eosin, toluidine blue) performed during Mohs
surgery. When a non-routine histochemical stain on frozen tissue is utilized,
report 88314 with modifier 59 or modifier XU-unusual, non-overlapping service.  
  
Do not report 88302-88309 on the same specimen as part of the Mohs surgery.  
  
Diagnosis(es) must be present on any claim submitted and must be coded to the
highest level of specificity.  
  
If repair is performed, use separate repair, flap, or graft codes. The repair
of wounds may be classified as simple, intermediate, or complex.  
  
 **Simple repair** is used when the wound is superficial, e.g., involving
primarily epidermis or dermis or subcutaneous tissue without significant
involvement of deeper structures and requires a simple one layer closure.  
  
 **Intermediate repair** includes the repair of wounds that, in addition to
the above, required layered closure of one or more of the deeper layers of
subcutaneous tissue and superficial (non-muscle) fascia, in addition to the
skin (epidermal and dermal closure).  
  
 **Complex repair** includes the repair of wounds requiring more than layered
closure, such as scar revision, debridement, extensive, undermining, stents or
retention sutures.  
  
Adjacent tissue transfer or rearrangement codes are used for excision
(including lesion) and/or repair of adjacent tissue transfer or rearrangement
(e.g., Z-plasty, W-plasty, V-Y plasty, rotation flap, random island flap,
advancement flap). Undermining alone of adjacent tissues to achieve closure,
without additional incisions, does not constitute adjacent tissue transfer.  
  
Skin graft necessary to close secondary defect is considered an additional
procedure. For purposes of code selection, the term "defect" includes the
primary and secondary defects. The primary defect resulting from the excision
and the secondary defect resulting from flap design to perform the
reconstruction are measured together to determine the code.  
  
 **Documentation Requirements**

  1. All documentation must be maintained in the patient's medical record and made available to the contractor upon request.
  2. Every page of the record must be legible and include appropriate patient identification information (e.g., complete name, dates of service[s]). The documentation must include the legible signature of the physician or non-physician practitioner responsible for and providing the care to the patient.
  3. The submitted medical record must support the use of the selected ICD-10-CM code(s). The submitted CPT/HCPCS code must describe the service performed.
  4. The physician must document in the patient's medical record that the diagnosis is appropriate for MMS and that MMS is an appropriate choice as the treatment of the particular lesion. Also, the options for care (both the primary procedure options and repair options) must be discussed with the patient and clearly noted in the pre-procedure (or post procedure as appropriate) documentation. In summary, the minimal medical need documentation entails that the beneficiary was informed of their treatment options and explained the risks/benefits of the MMS technique and associated repair.
  5. Operative notes and pathology documentation in the patient's medical record should clearly show that MMS was performed using accepted MMS technique, in which the physician acts in two integrated and distinct capacities: surgeon and pathologist (therefore confirming that the procedure meets the definition of the CPT code[s]).
  6. Operative documentation should note: location, number, and size of the lesion(s); number of stages performed; number of specimens per stage. Histology documentation must include the following: (a) First stage: depth of invasion; pathological pattern of the tumor; cell morphology; if present, note perineural invasion of scar tissue. (b) Subsequent stages: if the tumor characteristics are the same as in the first stage, note this fact only. If the tumor characteristics are different from the first stage, describe the differences.
  7. Measurement of the primary lesion necessitating MMS and measurements in support of repair or related procedures (such as but not limited to adjacent tissue transfer/rearrangements, grafts/flaps) completing the MMS procedure and confirming the primary defect measurement or other relevant measurements should be verifiable. Documentation of the clinical tumor border definition may be accomplished by preoperative photography with the skin stretched to delineate the visible clinical borders with or without debulking curettage (using a centimeter ruler or relation of size by another anatomic structure). Postoperative photography to document the defect may also be considered, especially for small lesions that have a significant subepithelial component (i.e., tip of the iceberg phenomenon). It is understood that photographic documentation may not be possible in a small percentage of cases because of technical difficulties.
  8. When the surgical defect created by MMS requires reconstruction, it should be clear on the documentation that the reconstructive technique performed was an appropriate choice to preserve functional capabilities and to restore physical appearance.
  9. If one of the NCCI associated modifiers (XE-separate encounter, XP-separate practitioner, XS-separate structure, XU-unusual, non-overlapping service) is used with a skin biopsy/pathology code on the same day the MMS was performed, physician documentation must clearly support the use of the modifier(s).
  10. If a pathology code is billed on the same day as MMS, documentation must support a separate excision/biopsy/repair was performed.