Billing code 21931: Back mass excisionMedicare rate & RVUs in Texas
Removal of a subcutaneous soft-tissue mass on the back or flank measuring at least 3 cm, rather than a biopsy or deep-tumor resection.
CMS doesn’t publish an office rate for 21931 in Texas.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
On this page 9 sections
What 21931 covers
This service removes a soft-tissue mass located in the subcutaneous tissue of the back or flank, with a mass size of 3 cm or greater. A common example is excision of a subcutaneous lipoma. The surgeon opens the skin, dissects the mass from surrounding tissue, removes it, and closes the wound. General surgeons and other surgeons who treat soft-tissue masses may perform the procedure in an office or surgical facility, depending on the case and setting.
Select the code based on the mass’s location, tissue plane, and size—not the length of the incision. The operative report should identify the back or flank site, establish that the mass was subcutaneous, document its size, and describe excision rather than sampling alone. CMS assigns a 90-day global period, including the day-before preoperative visit and 90 days of related postoperative care. For multiple procedures in one session, the highest-valued procedure is paid in full and other procedures are subject to the standard 50% reduction. An assistant at surgery may be paid; co-surgeons and team surgery are not permitted. A bilateral adjustment does not apply, and modifier 50 is inappropriate.
This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.
Where 21931 pays more and less in Texas
The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.
8 of 8 payment localities
| Payment locality | Office | Facility |
|---|---|---|
| Austin | Unavailable | $457.80 |
| Beaumont | Unavailable | $433.99 |
| Brazoria | Unavailable | $441.61 |
| Dallas | Unavailable | $447.03 |
| Fort Worth | Unavailable | $446.01 |
| Galveston | Unavailable | $444.62 |
| Houston | Unavailable | $475.01 |
| Rest Of Texas | Unavailable | $439.33 |
How the 21931 rate is calculated
Each of 21931’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.
How the rate is built · 21931
RVUs × geographic indexes × conversion factor
Swap in your local Medicare rate.
Work 6.71Practice expense 5.21Malpractice 1.66
All indexes start at 1.000 (the national rate). Enter a ZIP or drag a slider.
Payment rules and modifiers for 21931
21931 has a 90-day global period: related visits in that window are included in the surgery payment.
CMS payment indicators · 21931
Back mass excision
| Rule | CMS value | What it means |
|---|---|---|
| Global period | 090 | Major surgery: the day before, the day of, and 90 days after are included. |
| Multiple procedures | 2 | Standard reduction: highest-valued procedure at 100%, others at 50%. |
| Bilateral (modifier 50) | 0 | The 150% bilateral adjustment doesn’t apply. |
| Assistant at surgery (80/81/82/AS) | 2 | Paid. |
| Co-surgeons (62) | 0 | Not permitted. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 0 | Physician service: no professional/technical split. |
| Split (54/55/56) | 0.10/0.69/0.21 | Share of the payment for pre-op, the procedure itself, and post-op care. |
Global surgery period · 21931
Back mass excision
90-day global period ends
Dec 30, 2026
Covers Sep 30, 2026 through Dec 30, 2026 (92 days, including the day before surgery).
Visit on Oct 31, 2026
Day 30 of the 90-day post-op period: related follow-up care is included in the surgical payment.
Pre-op dayGlobal period
What modifiers do to the payment
Modifier 51 · payment effect
With and without the modifier
21931 without 51 · national facility
$453.58
Back mass excision
21931-51 · Second procedure: 50%
$226.79
When this isn’t the highest-valued procedure in the session, Medicare pays 50% of its fee schedule amount (the highest is paid at 100%).
21931 compared with similar codes
Compare codes
21931 vs 21930 vs 21932 vs 21933 vs 21920: national Medicare rates
Swap in your local Medicare rate.
How to choose
- 21930Soft-tissue excision
- Use 21930 for a subcutaneous back or flank mass under 3 cm. This code is for a mass measuring 3 cm or larger.
- 21932Back tumor excision
- Use 21932 when the back or flank tumor is deep rather than subcutaneous and measures under 5 cm.
- 21933Back tumor excision
- Use 21933 for a deep back or flank tumor measuring 5 cm or larger; this code describes a subcutaneous mass.
- 21920Soft-tissue biopsy
- Use 21920 when the service is a soft-tissue biopsy of the back, not excision of the subcutaneous mass.
21931 billing questions
How is this code distinguished from 21930?
Both describe removal of a subcutaneous soft-tissue mass of the back or flank. Use 21931 when the mass is 3 cm or larger; 21930 is for a mass under 3 cm.
Does this code cover a biopsy of the mass?
No. This code represents excision of the subcutaneous mass. When the service samples tissue rather than removing the mass, consider the applicable back soft-tissue biopsy code.
What documentation supports reporting this code?
Document the back or flank site, the subcutaneous tissue plane, the mass size, and the operative work showing removal. The record should distinguish the service from a biopsy or excision of a deep mass.
Should modifier 50 be used for masses on both sides?
No. CMS bilateral adjustment does not apply to this code, and modifier 50 is inappropriate.
What postoperative care is included in the global period?
The 90-day global period includes the day-before preoperative visit and 90 days of related postoperative care.
Where these rates come from
FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.
CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027
Show the CMS file lines behind this rate
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