21925

Deep soft tissue biopsy of the back or flank, requiring dissection below the superficial fascia to obtain a tissue specimen for pathological analysis.

Verified May 8, 2026 · 7 sources ↓

Medicare: $543.10
Work RVU: 4.51
Global, days: 90
Region: Spine

Drawn from CMSAAPCFindacodeCgsmedicareNIH

Documentation requirements

What must appear in the operative or office note to support the claim.

Source · Editorial brief grounded in 7 cited references ↓

Explicit confirmation of deep/subfascial dissection depth in the operative note — not just 'soft tissue biopsy of the back'
Anatomic location of the lesion within the back or flank, including laterality when applicable
Pre-operative imaging (MRI or ultrasound) documenting lesion depth and characteristics
Specimen submission documentation confirming tissue sent to pathology with laterality and depth noted
Clinical indication tying the biopsy to a specific diagnosis or differential (e.g., soft tissue mass, rule out sarcoma)
Operative note detailing the surgical approach, instruments used, and wound closure method

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 24 Unrelated E/M during global 25 Significant separate E/M 50 Bilateral procedure 51 Multiple procedures 52 Reduced services 58 Staged or related 59 Distinct service 76 Repeat, same physician 77 Repeat, another physician 78 Unplanned return — related 79 Unrelated during global LT Left side RT Right side XS Separate structure

What this code covers

Source · Editorial summary grounded in 7 cited references ↓

CPT 21925 covers a deep soft tissue biopsy of the back or flank — distinct from the superficial counterpart (21920), this code applies when the surgeon dissects through fascia to sample tissue in the deeper muscular or subfascial layers. The procedure is performed when imaging or clinical exam identifies a suspicious mass in the deeper tissues that requires histological diagnosis, most commonly to rule out sarcoma, metastatic disease, or other neoplastic processes.

The 90-day global period means the initial postoperative visits, wound checks, and suture removal are all bundled. Any evaluation of a new or unrelated problem during that window requires modifier 24 (E/M) or 25 (same-day E/M prior to procedure). If pathology returns malignant and a more definitive resection is planned within the global period, that re-excision bills with modifier 58 as a staged procedure.

The code sits in the Excision Procedures on the Back and Flank section. Depth documentation is the single biggest audit trigger — if the operative note doesn't explicitly confirm subfascial or deep tissue dissection, payers will downcode to 21920. Imaging correlation (MRI or ultrasound showing lesion depth) strengthens the record when depth is close to the fascial boundary.

RVU & reimbursement

Component RVUs and Medicare national rate. Actual payment varies by GPCI locality.

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU vs. total RVU

The work RVU (4.51) is the surgeon's own effort — the figure physician pay and productivity targets are built on. The total RVU (16.26) adds practice overhead and malpractice, and is what drives the Medicare payment below.

Work RVU	4.51
Practice expense RVU	10.72
Malpractice RVU	1.03
Total RVU	16.26
Medicare national rate	$543.10
Global period	90 days

Payment by site of service

Medicare pays different rates by setting. HOPD typically pays substantially more than ASC for the same procedure.

Source · CMS OPPS Addendum B·ASC HCPCS payment rates·2026

Setting	Medicare rate (national)
Office (PFS non-facility) Procedure performed in physician's office	$543.10
HOPD (APC 5072) Hospital outpatient department	$1,687.37
ASC (PI A2) Ambulatory surgical center (freestanding)	$742.04

Common denial reasons

The recurring reasons claims for CPT 21925 get rejected.

Source · Editorial brief grounded in CMS NCCI edits, AAOS coding appeals, and cited references ↓

Depth not documented — payer downcodes to 21920 (superficial) when 'deep' or 'subfascial' is absent from the operative note
Missing or inadequate pathology linkage — claim submitted without corresponding pathology specimen documentation
Global period conflict — follow-up E/M billed without modifier 24 during the 90-day postoperative window
Laterality mismatch between operative report and claim when LT/RT modifiers are appended
Medical necessity not established — no imaging or clinical documentation supporting why biopsy was required at this depth

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 7 cited references ↓

01What separates 21925 from 21920?

Depth. 21920 is superficial soft tissue — above the fascia. 21925 requires dissection through fascia into the deep soft tissue layer. If your operative note doesn't say 'subfascial' or 'deep,' expect a downcode to 21920.

02Does 21925 carry a global period?

Yes — 90-day global. Routine post-op visits, wound checks, and suture removal are all bundled. Bill a related procedure within that window with modifier 78 (unplanned, related return to OR) or 58 (planned staged procedure). Unrelated procedures need modifier 79.

03Can you bill 21925 with a same-day E/M?

Yes, if the E/M is a separately identifiable service beyond the decision to perform the biopsy. Append modifier 25 to the E/M. Document that the visit addressed issues beyond biopsy planning — a generic pre-procedure note without modifier 25 will bundle.

04Is modifier 50 appropriate if biopsies are taken bilaterally?

Yes. If deep soft tissue biopsies are performed on both sides of the back or flank during the same session, append modifier 50. Bill the primary code without a modifier for the first side; some payers require two line items with LT and RT instead — verify payer preference before submitting.

05If the pathology comes back malignant and a wider resection is needed within the 90-day global, how do you bill the resection?

Use modifier 58 on the resection code. The 90-day global does not bundle a subsequent, more definitive surgical procedure that was staged or planned after the biopsy results. Modifier 58 signals a staged or related procedure, not a complication return.

06When should modifier 22 be appended to 21925?

When the procedure required substantially greater work than typical — for example, a lesion adjacent to major neurovascular structures requiring extended dissection, or a patient with prior back surgery creating significant scar tissue. You need documentation quantifying the added complexity and time; without it, payers will strip the modifier and reduce payment.

07Is 21925 payable in an ASC setting?

Yes. The ASC payment rate differs from the HOPD rate — see the Site of Service comparison on this page. Confirm the procedure is on your ASC's covered procedures list, as ASC coverage is payer- and contract-specific.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

Mira AI Scribe

Mira's AI scribe captures the lesion's anatomic location, confirmed dissection depth (subfascial vs. superficial), surgical approach, and specimen handling details directly from dictation. This prevents the most common denial for 21925 — a vague operative note that fails to confirm deep tissue dissection, triggering an automatic downcode to 21920.

See how Mira captures CPT 21925 documentation