Deep soft tissue biopsy of the thigh or knee area, performed at or below the fascial layer (subfascial or intramuscular), requiring incision through skin and fascia to obtain a tissue sample for pathologic analysis.

Verified May 8, 2026 · 6 sources ↓

Medicare: $402.48
Total RVUs: 12.05
Global, days: 90
Region: Knee

Drawn from CMSGenhealthAAPCEmedny

Documentation requirements

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

Source · Editorial brief grounded in 6 cited references ↓

Specify tissue depth explicitly — subfascial or intramuscular — not just 'deep tissue'
Name the anatomic location within the thigh or knee (e.g., anterior compartment, vastus lateralis, popliteal fossa)
Document the surgical approach: incision through skin and fascia, instruments used for tissue sampling
Record the indication: tumor, suspected malignancy, infection, inflammatory mass, or other abnormality requiring tissue diagnosis
Include specimen submission confirmation — pathology requisition or operative note notation that specimen was sent to pathology
Document anesthesia type and patient positioning to support medical necessity of surgical (vs. image-guided) approach

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 50 Bilateral procedure 51 Multiple procedures 52 Reduced services 58 Staged or related 59 Distinct service 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 6 cited references ↓

CPT 27324 covers an open deep biopsy of soft tissue in the thigh or knee region — specifically tissue residing beneath the fascia or within muscle. The surgeon makes an incision through skin and fascia, excises a representative tissue sample using a scalpel or biopsy needle, and closes the wound. The specimen goes to pathology to characterize tumors, infection, or inflammatory processes. This is a diagnostic procedure; if the same session proceeds to excision of the lesion, the excision code drives billing and 27324 is not separately reported.

The 90-day global period bundles all routine post-op care through day 90. A separate E/M in that window requires modifier 24 (unrelated) or 25 (significant separate service on the same day as a minor procedure, though 27324 itself carries a 90-day global). Staged or unrelated procedures during the global need modifier 79; a return to the OR for a related complication uses modifier 78.

Code selection between 27323 (superficial) and 27324 (deep) depends entirely on tissue depth relative to the fascia — not incision size. Billing 27323 when the operative note documents subfascial or intramuscular access is a common audit target. Likewise, 27324 and 20205 (deep muscle biopsy, any site) overlap; 27324 is the site-specific code for thigh or knee and is preferred when the anatomic site is clearly documented.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	4.91
Practice expense RVU	6.01
Malpractice RVU	1.13
Total RVU	12.05
Medicare national rate	$402.48
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	$402.48
HOPD (APC 5073) Hospital outpatient department	$2,967.63
ASC (PI A2) Ambulatory surgical center (freestanding)	$1,248.36

Common denial reasons

The recurring reasons claims for CPT 27324 get rejected.

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

Billed as 27324 but operative note describes superficial (above fascia) sampling — payer downcodes to 27323
27324 bundled when billed same session as soft tissue excision (27327, 27328, 27329) — biopsy is included in the excision
Missing or vague pathology specimen documentation — payer cannot confirm diagnostic intent
Incorrect site-specificity when 20205 was coded instead of 27324, or vice versa, without anatomic justification
Lack of medical necessity documentation — no imaging, prior workup, or clinical finding supporting need for open deep biopsy over fine needle aspiration

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 6 cited references ↓

01When should I use 27324 instead of 27323?

Use 27324 when the biopsy reaches below the fascial layer — subfascial or intramuscular. If the surgeon samples tissue above the fascia, 27323 is correct. Depth relative to fascia is the deciding factor, not incision length or anesthesia type.

02Can 27324 be billed on the same day as a soft tissue excision like 27328?

No. When the surgeon proceeds to excision of the biopsied lesion in the same session, the excision code (27328 or 27329) represents the definitive work. 27324 is not separately reported — it is included in the excision.

03How does the 90-day global period affect post-op billing for 27324?

All routine follow-up care through post-op day 90 is bundled. E/M visits during that window for an unrelated condition need modifier 24. A return to the OR for a related complication (e.g., hematoma evacuation) requires modifier 78; for an unrelated procedure, use modifier 79.

04What distinguishes 27324 from 20205?

20205 is a general deep muscle biopsy code applicable anywhere in the body. 27324 is site-specific to the thigh or knee. When the operative site is clearly documented as thigh or knee, 27324 is the appropriate code and is preferred over the general 20205.

05Is modifier 50 appropriate for 27324?

Bilateral deep thigh or knee biopsies performed at the same session can be reported with modifier 50, but this is clinically uncommon. Document distinct lesions and bilateral sites clearly in the operative note — vague documentation of 'bilateral' without separate lesion description will not survive audit.

06Does site of service affect reimbursement for 27324?

Yes. HOPD and ASC payments differ substantially from the professional fee schedule rate. See the Site of Service comparison table on this page for the 2026 facility payment amounts.

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 tissue depth (subfascial vs. intramuscular), the named anatomic compartment, the surgical approach through fascia, and the pathology specimen disposition directly from dictation. That specificity locks in 27324 over 27323 and defends against bundling denials when an excision code is billed at a separate encounter.

See how Mira captures CPT 27324 documentation