Billing and Coding: Mohs Micrographic Surgery

The following coding and billing guidance is to be used with its associated
Local Coverage Determination.

As defined by the American Medical Association Current Procedural Terminology
(American Medical Association, Chicago, IL), Mohs Micrographic Surgery (MMS)
is a technique for the removal of complex or ill-defined skin cancer with
histologic examination of 100% of the surgical margins. It is a combination of
surgical excision and surgical pathology that requires a single physician to
act in 2 integrated but separate and distinct capacities: surgeon and
pathologist. The Mohs surgeon removes the tumor tissue and maps and divides
the tumor specimen into pieces, and each piece is embedded into an individual
tissue block for histopathologic (hematoxylin-eosin or toluidine blue)
examination. Thus, a tissue block in MMS is defined as an individual tissue
piece embedded in a mounting medium for sectioning.

If a surgeon performs an excision using Mohs surgical techniques but does not
personally provide the histologic evaluation of the specimen(s), the CPT
codes for MMS shall not be used. Instead standard excision codes should be
chosen for such medically necessary services (e.g., 11600 - 11646).

Medicare is aware that a biopsy of the skin lesion for which Mohs surgery is
planned may be 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 planned. To allow separate payment for a
nonroutine histochemical stain on frozen tissue during Mohs surgery, report
88314 with modifier 59.

If a prior biopsy of the site undergoing Mohs surgery has been previously
performed within the last 60 days, the surgeon should make a reasonable effort
to obtain those results rather than repeating the biopsy.

Reporting both Mohs Micrographic Surgery CPT codes 17311-17315 and Surgical
Pathology CPT 88302-88309 or 88331-88332 on tissue used for margin evaluation
during Mohs surgery is inappropriate and will indicate that true Mohs surgery
was not done. Such claims for Mohs surgery (17311-17315) will be denied. There
are occasional clinical situations in which tissue separate from the tissue
examined during Mohs surgery is appropriately submitted for subsequent
formalin fixed processing and histopathologic examination. The submitted
tissue is not the same tissue that was processed during the Mohs surgery. It
may constitute a tissue margin beyond that evaluated with Mohs surgery or it
may involve a totally unrelated tissue specimen. In such situations both the
Mohs surgery and the histopathology are subject to coverage. In such cases the
clinical record must clearly show the reasoning for the histopathologic
specimen and interpretation. To allow separate payment for a biopsy and
pathology on a separate skin lesion, other than the lesion for which Mohs
surgery is performed on the same day, the -59 modifier is appropriate.

If reporting the -59 modifier with a skin biopsy/pathology code on the same
day the Mohs surgery was performed, the physician's documentation should
clearly indicate:

  * That the biopsy was performed on a lesion other than the one on which Mohs surgery was performed;
  * If the biopsy is of the same lesion as the Mohs lesion, that a biopsy of that lesion had not been done within the previous 60 days; or
  * If there has been a recent (within 60 days) biopsy of the same lesion as the Mohs lesion, the results of that biopsy were unobtainable despite reasonable effort by the Mohs surgeon.

  **Documentation requirements**

The majority of simple skin cancers can be managed by simple excision or
destruction techniques. The medical records should clearly show that Mohs
surgery was chosen because of the complexity, size and/or location of the
lesion and why other approaches are not medically necessary and reasonable.
The operative notes and pathology documentation in the patient's medical
record must clearly show that Mohs micrographic surgery was performed using
accepted Mohs technique, with the same physician performing both the surgical
and pathology services. The notes should also contain the location, number and
size of the lesion(s), the number of stages performed, and the number of
specimens per stage.

Documentation must be available to Medicare contractors upon request.

The Mohs surgeon must describe the histology of the specimens taken in the
first stage. That description should include depth of invasion, pathological
pattern, cell morphology, and, if present, perineural invasion or presence of
scar tissue. For subsequent stages, you may note that the pattern and
morphology of the tumor (if still seen) is as described for the first stage;
or, if differences are found, note the changes. There is no need to repeat the
detailed description documented for the first stage, presuming that the
description would fit the tumor found on subsequent stages.

The patient's medical record must contain documentation that fully supports
the medical necessity for services included within this LCD in accordance with
this LCD. This documentation should include, but is not limited to, relevant
medical history, physical examination, and results of pertinent diagnostic
tests or procedures including biopsy reports along with the procedural note.

**Sources:**

American Medical Association. Mohs Micrographic Surgery. CPT Assistant
2006;16:1-7