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'X' Modifiers in Dermatology
Last Updated: 07/12/2016
UPDATE! (2/12/2015)

On 1/26/2015, CMS issued an updated bulletin on the new 'X' modifiers. CMS has stated that providers can continue to use modifier 59 if they were using it appropriately before.

We are starting to receive some reports of some providers that have been successful in getting reimbursed using XS on their claims. Initially some providers were receiving denials, but reports are that some carriers are now getting their systems current with the new modifiers. However, we continue to advice that providers must proceed with caution and use the new 'X' modifiers at your own risk.

ECS has recommended since January 1, 2015 that providers continue to use modifier 59 for this exact reason. We suspected there would be confusion with all of the carriers. The Medicare Contractors (i.e., Noridian, WPS Medicare, First Coast, Palmetto, etc.) have only received the same single document for guidance on these new modifiers without any further guidance, instructions, or detailed examples.

ECS continues to be in contact with educators at several of the Medicare carriers as well as the Education coordinators at the American Academy of Dermatology. In addition, we have held discussions with various coding professionals and consultants across the country and in multiple specialties. Everyone is in agreement (including the Medicare contractor’s themselves) that CMS roll-out of the new ‘X’ modifiers has been unacceptable.

The QuickCheck screen in DermCoder will guide you as to where to place modifier 59 appropriately. QuickCheck will continue to output “59 or XS*”. Please refer to the “More info” button in the right side of the screen. It will take you directly to this page.

Again, ECS recommends that providers continue to use modifier 59 if they were using it appropriately before (i.e. for separate and distinct lesions or procedures.)


On August 15, 2014, CMS released a new MedLearn Matters article concerning four new modifier choices available January 1, 2015 for bundled services. These four new modifiers are to be used as a subset (i.e., more specific version) of the commonly used Modifier -59

Link to article:

Comments from ECS:

Note: CMS (i.e., Medicare) states that this policy is effective January 1, 2015 with an implementation date of January 5, 2015. Basically, January 2015.

It is important to note that CMS will continue to recognize modifier -59, but is proposing four new "more specific" modifiers that can also be used (in place of modifier -59) if the situation applies.

It is ECS' recommendation that you continue to use modifier 59 at this time, unless you have notification from a carrier that theyrequire the more specific X modifiers. At this time, we have not come across any carrier that is exclusively requiring the use of X modifiers. However, we have added XS information in QuickCheck so you can see where it may be used appropriately, if your carrier accepts them.

For 2015, the new "more specific" modifiers (in place of modifier -59), include:

-XE Separate Encounter: A Service That Is Distinct Because It Occurred During A Separate Encounter
-XS Separate Structure: A Service That Is Distinct Because It Was Performed On A Separate Organ/Structure
-XP Separate Practitioner: A Service That Is Distinct Because It Was Performed By A Different Practitioner
-XU Unusual Non-Overlapping Service: The Use Of A Service That Is Distinct Because It Does Not Overlap Usual Components Of The Main Service.

The MedLearn Matters article also mentions that certain carriers may require these new modifiers on certain "high risk" bundles. However, CMS has yet to specify what those "high risk" bundles are at this time.

Important: This new modifier is being released by CMS. We have only seen written guidance from a few commercial carriers that they will accept the new X modifiers in place of modifier 59. It remains to be seen how many non-Medicare payors (i.e., commercial carriers) will adopt the new modifiers.

In its transmittal, CMS reminds you that CPT instructions say that modifier -59 should not be used when there is a "more specific" modifier available. (e.g., LT, RT, FA, F1-F9, TA, T1-T9, E1-E4, etc.) Providers/Coders are encouraged to make sure they understand the proper use of -LT and -RT modifiers versus modifier -59 (see the end of this article).

What does all this mean to dermatology providers and billers?

Our analysis is that the new XS modifier "may" be the most common new modifier used by dermatologists. Again, don't panic yet! They are saying that CMS carriers will still let you use modifier 59 for the time being.

Lets look at the new and old definitions of XS versus modifier 59...

-XS Separate Structure: A Service That Is Distinct Because It Was Performed On A Separate Organ/Structure

The CPT definition of Modifier 59 is

"Distinct Procedural Service: Under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-E/M services performed on the same day. Modifier 59 is used to identify procedures/services, other than E/M services, that are not normally reported together, but are appropriate under the circumstances. Documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same individual. However, when another already established modifier is appropriate it should be used rather than modifier 59. Only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used. Note: Modifier 59 should not be appended to an E/M service. To report a separate and distinct E/M service with a non-E/M service performed on the same date, see modifier 25.

The official CMS National Correct Coding Initiative Modifier 59 instructions state:

"Modifier 59 is used appropriately for different anatomic sites during the same encounter only when procedures which are not ordinarily performed or encountered on the same day are performed on different organs, or different anatomic regions, or in limited situations on different, non-contiguous lesions in different anatomic regions of the same organ."


This is the most common scenario where modifier 59 is applied in the specialty of dermatology (i.e., when ordinarily bundled services are performed on separate and distinct lesions.)

Therefore, modifier XS = modifier 59 in most instances for dermatology, when used on separate and distinct lesions.

Note: There is some uncertainty and speculation that XS modifier wouldn't apply to dermatology because the skin is considered the same organ. However, it is our opinion and that of several national coding experts that separate "structure" in the XS definition was meant to encompass "different site or organ system, separate incision/excision, separate lesion, or separate injury"

Let’s look at some examples:

Example 1:

In 2014, a dermatologist performs two separate surgical services, for example, destroys some AKs (CPT 17000/17003) on the face and biopsies a separate lesion (CPT 11100) on the trunk. Ordinarily, under the pre-January 2015 Correct Coding Initiative modifier rules, CPT code 11100 would receive modifier -59.

11100 -59


Example 2:

Under the new 2015 rules, if the AKs are on the face and the biopsied lesion is on the trunk, these are considered a separate structures and modifier -XS is the most appropriate. In other words, starting January 2015, you could also now bill:

11100 - XS

Note: The current regulations state that modifier -59 will also still be accepted for the time being. Therefore, until further notice, you could use either -XS or -59 on the 11100 (but not both).

Example 3:

Now, it is also clear that if the AKs are on the face (forehead) and the biopsy is on the lip (CPT 40490), these are clearly different structures (based on the site-specific biopsy code for the lip) and modifier -XS also applies. You could now bill:

40490 -XS

Note: The current regulations state that modifier -59 will also still be accepted for the time being. Therefore, until further notice, you could use either -XS or -59 on the 40490 (but not both).

Are the new modifiers mandatory?

The final instructions on Page 3 states, "As a default, at this time CMS will initially accept either a -59 modifier OR a more selective - X{EPSU} modifier as correct coding, although the rapid migration of providers to the more selective modifiers is encouraged."

However, please note that these modifiers are valid even before national edits are in place. MACs are not prohibited from requiring the use of selective modifiers in lieu of the general -59 modifier, when necessitated by local program integrity and compliance needs.”

In a nutshell, this is stating that providers/billers can continue to use modifier -59 after January 2015. It’s also stating that some carriers may begin accepting the new - X{EPSU} modifiers earlier than January 2015.

Additional thoughts from ECS regarding modifiers XE, XP, XS, and XU

1. Modifier XE is intended for the instance that normally bundled procedures are performed on separate encounters during the same day. Since most bundled dermatologic services are performed/billed on the same date of service and during the same session, XE does not ordinarily apply. It would be rare to use this new modifier.

Example: 4

A patient has some some AKs destroyed during an office visit early in the day. The patient goes home and falls off his/her bicycle requiring a trip back to the dermatologist to have some sutures placed (simple repair). You bill

12002 -XE

A non-dermatology example would be a patient having an ECG in the morning, and then coming back for a Stress Test later in the afternoon during a different session. Normally these services are bundled and require modifier 59. Modifier XE would be used to indicate that these ordinarily bundled procedures were performed on separate encounters.

2. Modifier XP is intended to show that a bundled service was performed by a different provider. Most bundled dermatologic services are performed and billed by a single provider. Modifier XP, for example, might be used for bundled general anesthesia/surgical procedures that might be performed by a separate provider. Modifier XP would not ordinarily apply to dermatology.

3. Modifier XU is intended to be used for unusual non-overlapping services. Unfortunately, CMS has not provided any guidance on what that actually means. ECS attended several teleconferences by two different Medicare contractors, and they too were unable to provide an example of when modifier XU might be necessary. At this time, modifier XU is not applicable to dermatology.

4. Do not apply both modifier 59 and one of the new 'X' modifiers. It’s an either/or scenario. If, ordinarily, modifier 59 applies, but you know these are performed on separate structures (face versus lower extremity), then you can definitely bill with a modifier XS or modifier 59, but not both.

LT, RT, FA, F1-F9, TA, T1-T9, and E1-E4 instead of Modifier -59

Medicare states that modifier -59 should be used when more specific modifiers are not available.

For example, for CCI bundled services that are performed on the left and right side of the body, respectively, Medicare will also accept an -LT modifier (left side) or an -RT modifier (right side) for the procedures performed on each respective side of the body. Even though the two procedures are bundled with the CCI and one of the codes would ordinarily require modifier 59, by adding an -RT or -LT to each code (depending on which side the lesions were on), you are letting the carrier know that the lesions are indeed on separate areas of the body. Therefore, modifier -59 is not needed for this CCI bundle. Again, modifier -59 isn’t needed because a more specific modifier is already being used (e.g., -LT or -RT were applied to each code).

For years, CMS (and most carriers) have also accepted the more generic -59 modifier (in lieu of -LT and -RT and other site-specific modifiers). The site-specific modifiers have never been mandatory. We are doubtful they will begin enforcing use of these modifiers at this time.

Example 5:

A dermatologist performs two separate surgical services. He/she destroys some AKs (CPT 17000/17003) on the left arm and also biopsies a separate lesion (CPT 11100) on right leg. Since more specific modifiers are available (other than modifier -59), CMS would also allow you to bill:

17000 -LT
17003 -LT
11100 -RT (would normally only get modifier -59)

The presence of BOTH modifiers -LT and -RT tells the carrier that these services were performed on separate areas of the body (left side versus right side) and therefore, modifier -59 is not even needed.

The acceptance of the -LT and -RT (and similar site-specific modifiers) varies by carrier, and providers/billers should check with their local carriers (and commercial carriers) to determine if they prefer these site-specific modifiers versus modifier -59/XS.

About DermCoder and QuickCheck

DermCoder has always had a provision to turn this off if your carrier doesn't want you to use modifier 59 with add-on codes when the primary code also gets modifier 59.

Because DermCoder doesn't know if this is a commercial claim or Medicare (and what your carrier's rules are), you have the option to turn that feature ON or OFF on a case-by-case basis by simply clicking a check box . This feature has always been there. (Look right above the check boxes in QuickCheck).


ECS will continue to seek clarification and will post more information as we know more.

However, providers/billers can begin to prepare to use modifier -XS, in most instances. Again this will apply to Correct Coding Initiative bundled pairs, in place of modifier 59, when the services are performed on separate lesions or on separate areas/structures of the body.

And as a final reminder, according to the recently released MedLearn matters, CMS will continue to recognize modifier 59 for the time being.

The good news is that DermCoder's QuickCheck will be updated, to reflect these changes and provide proper guidance starting in January 2015.

Again, it is our recommendation that your practice continue to use modifier 59 in the same manner you have been for many years.The QuickCheck screen in DermCoder will guide you as to where to place modifier 59 appropriately. QuickCheck will continue to output “59 or XS*”. Please refer to the “more info” button in the right side of the screen for detailed explanation of these new modifiers.

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Copyright 2014, Ellzey Coding Solutions, Inc. All rights reserved. The contents of this article may not be reproduced/redistributed/transmitted or disseminated in any fashion or format, without the express written consent of Ellzey Coding Solutions, Inc.

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