CPT code 10004: Add-on code for each additional FNA lesion

Key Takeaways

CPT code 10004 is the add-on code for fine needle aspiration biopsy without imaging guidance on each additional lesion – it has no first-lesion descriptor and is never billed by itself

CPT 10004 must always be reported alongside CPT 10021, the primary first-lesion code. In the 2019 FNA restructuring, the AMA deleted code 10022, not 10021 – 10021 was revised to add a first-lesion descriptor, and +10004 was created as its new add-on partner

The CAP Medicare Physician Fee Schedule impact tables put the non-facility rate for +10004 at approximately $51.75 (2025) to $52.44 (2026), against roughly $97.69 (2025) to $100.54 (2026) for primary code 10021 – verify current figures via the CMS Physician Fee Schedule Look-Up Tool

Pabau’s claims management software helps practices link procedure documentation to the correct primary-plus-add-on code pair at the point of care, catching a standalone CPT 10004 claim before it goes out the door

CPT code 10004 is an add-on code. It covers each additional lesion sampled without imaging guidance in the same session, and it can only be reported alongside CPT 10021, the primary first-lesion code.

The mix-up traces back to the AMA’s 2019 restructuring of the FNA code set, which replaced a two-code system with ten codes in one pass.

CPT code 10004: Description and role as an add-on code

The American Medical Association (AMA) defines CPT code 10004 as: Fine needle aspiration biopsy, without imaging guidance; each additional lesion (List separately in addition to code for primary procedure).

In the CPT code book it’s printed as +10004. The leading “+” is the AMA’s standard symbol marking it as an add-on code, though claims are filed with the plain numeric code.

CPT 10004 sits in the General subsection of the CPT Surgery codes, home to the Fine Needle Aspiration Biopsy codes 10004 through 10021. That’s just before the Integumentary System subsection begins at code 10030, which also covers 10035. CPT 10004 has been in effect since January 1, 2019.

Fine needle aspiration biopsy uses a thin needle to withdraw cells or fluid from a mass or lesion for cytological analysis, with no incision required.

It’s commonly performed on thyroid nodules, lymph nodes, salivary gland masses, and superficial soft tissue lumps that a clinician can locate and sample by palpation alone.

CPT +10004 applies only when the clinician performs the additional aspiration entirely by palpation, with no real-time imaging used to guide needle placement, and only when a first lesion in that same session was already reported under CPT 10021.

If ultrasound, CT, fluoroscopy, or MRI guided the needle, a different add-on code in the 10004-10012 family applies instead, not +10004.

The 2019 FNA restructuring: What changed, and why

Before 2019, the FNA code family had two members: 10021 (without imaging guidance) and 10022 (with imaging guidance, which also required a separate radiological guidance code such as 76942). Neither distinguished between a first and an additional lesion, and neither identified which imaging modality was used.

Effective January 1, 2019, the AMA CPT Editorial Panel restructured the set to match how FNA is actually performed and resourced:

• CPT 10022 was deleted. It is not a valid code on any claim dated January 1, 2019 or later.
• CPT 10021 was revised, not retired. Its descriptor was updated to add “first lesion,” making it the current, active primary code for a non-image-guided FNA. It remains in full use today.
• Nine new codes were created – 10004 through 10012 – building the imaging modality directly into the code so a separate radiology guidance code is no longer needed. Each modality got a first-lesion primary code and a matching “each additional lesion” add-on code.

+10004 is one of those nine new codes. It was created specifically as the add-on partner to the revised CPT 10021, mirroring the first/each-additional pattern the AMA applied to every imaging modality: 10005/+10006 for ultrasound, 10007/+10008 for fluoroscopy, 10009/+10010 for CT, and 10011/+10012 for MRI.

It has never had a “first lesion” descriptor and was never a standalone code. Some billing resources get this backward, treating +10004 as if it replaced 10021.

If anything was replaced in 2019, it was 10022. Its replacement is the imaging-guided 10005-10012 series, not +10004.

The complete FNA code family: Primary and add-on pairs

Selecting the correct pair requires two decisions: whether imaging guidance was used and what type, and whether a given lesion is the first or an additional one in that session. For how the AMA differentiates complexity tiers across specialties more broadly, see CPT code selection.

Notice the pattern: every add-on code in this family (10004, 10006, 10008, 10010, 10012) is never reported alone, and each one only pairs with the primary code for its own imaging modality. Practices sampling multiple lesions without imaging in one session use 10021 for the first lesion and +10004, once per additional lesion, for every lesion after that.

For a look at how the primary code itself works in detail, see the companion reference on 10021.

When to use CPT 10004: The decision logic for additional lesions

The imaging and lesion-count decisions happen at the time of the procedure, not at the time of coding. Accurate clinical documentation in the patient record must capture the guidance method and the lesion count before the claim goes out.

Use this logic to select the correct codes:

1. Was any real-time imaging used to guide needle placement, for any lesion in the session? If no, the primary code is 10021. If yes, identify the modality (ultrasound, fluoroscopy, CT, MRI) and use the matching first-lesion code (10005, 10007, 10009, or 10011) instead.
2. Was only one lesion sampled in the session? If yes, stop – report only the primary code once. Do not add +10004 or any other add-on code.
3. Were additional lesions sampled in the same session, without imaging? If yes, report +10004 once for each additional lesion, alongside CPT 10021 on the same claim. Never report +10004 on a claim that doesn’t also include 10021.
4. Does the procedure note explicitly state no imaging was used and list each lesion sampled? If the note is silent on either point, the claim is vulnerable to audit. Document proactively.

Endocrinology and head/neck surgery practices sampling multiple palpable thyroid nodules or cervical lymph nodes in one visit, without ultrasound, are the most common clinical scenario for +10004.

Dermatology practices see the same pattern for superficial soft tissue lumps, and primary care practices sampling a palpable lump in the office rather than referring out add to the volume too.

Radiology departments performing image-guided FNA should almost never use it. Their add-on code is 10006, 10008, 10010, or 10012, depending on modality.

Can CPT 10004 be billed alone? Why the add-on rule matters

No. CPT +10004 has no independent value on a claim filed on the CMS-1500 form. It describes work that only makes sense in addition to a first-lesion procedure that’s already been billed. Because of that, payers process it strictly as a companion code:

• Claims editing systems reject +10004 without its primary code. Medicare’s National Correct Coding Initiative (NCCI) and most commercial claims editors check that an add-on code’s required primary procedure code (10021) appears on the same claim. If it doesn’t, +10004 denies outright, regardless of documentation quality.
• +10004 carries no separate global period or standalone RVU logic. Its relative value units are priced as incremental work on top of 10021, which is why the payment for +10004 is lower than for 10021 – it doesn’t recreate all the setup, consent, and overhead already captured in the primary code.
• A superbill or charge master that lists +10004 as an alternative to 10021, rather than as its add-on, will generate this exact denial pattern across every claim built from it – which is the root cause worth fixing, not just the individual rejected claim.

If your billing team has ever been told “use 10004 for the first lesion, it replaced 10021” – that guidance is backward, and it’s worth auditing recent claims and charge capture templates for the error before it compounds.

CPT 10004 fee schedule and Medicare reimbursement rates

The CMS Physician Fee Schedule sets reimbursement for both codes annually. Because +10004 is only ever billed with 10021, it’s most useful to look at the pair together. Per the College of American Pathologists’ published Medicare Physician Fee Schedule impact tables, the national non-facility (office-setting) payment amounts are:

CMS reviewed the entire FNA code family (10021, +10004, 10005, +10006) as a potentially misvalued set during recent rulemaking cycles. Both times, it declined to change the valuation, concluding the RVUs already reflect the typical work and practice-expense inputs involved.

Facility-setting rates are lower than non-facility rates for both codes, since practice-expense costs shift to the facility rather than the billing physician.

Geographic Practice Cost Index (GPCI) adjustments mean the paid amount varies by locality, and figures change with each annual fee schedule update. Confirm the current-year, locality-specific rate using the fee schedule lookup tool before billing.

Medicaid rates vary by state and are typically lower than Medicare. Commercial payers may use their own contracted fee schedules.

Modifiers and NCCI rules for CPT 10004

Because +10004 is an add-on code, several modifier rules apply differently than they would to a standalone procedure code. Verify payer-specific policy before billing, as requirements vary across commercial plans.

The core NCCI rule to remember: +10004 is designed to pair with 10021 in the same session, so no modifier is needed to “unbundle” them. They’re billed together by definition.

Do not bill a separate imaging guidance code, such as ultrasound guidance, alongside +10004. By definition, this code family involves no imaging, and adding one signals upcoding.

Cytopathology codes (e.g., 88172, 88173) may be billed separately from the FNA codes when performed, as they represent distinct services.

For practices managing complex FNA billing workflows across multiple providers, claims management software like Pabau supports modifier tracking at the claim level and flags when an add-on code is submitted without its required primary code.

ICD-10 diagnosis codes used with CPT 10004

Medical necessity for the FNA session is established through the ICD-10-CM diagnosis code(s) tied to each lesion sampled.

Because +10004 covers additional lesions in the same session as 10021, each lesion’s diagnosis code should reflect that lesion’s specific clinical finding rather than a single generic code reused across lines.

For a complete lookup reference, the AAPC CPT-to-ICD-10 crosswalk maps common procedure codes to compatible diagnosis codes.

If cytology confirms a benign thyroid neoplasm, the follow-up claim uses diagnosis code D34 rather than the working diagnosis used to justify the FNA itself.

Payers may deny a +10004 line when the linked diagnosis code doesn’t establish medical necessity for that specific additional lesion. Document the clinical rationale for each lesion sampled, not just the encounter overall.

Documentation requirements for CPT 10004 claims

The procedure note is the single most important document for defending a +10004 claim. It has to prove two things at once: that this is genuinely an additional lesion, and that the primary lesion (billed under 10021) was also documented in the same encounter.

Practices using digital forms and structured procedure note templates reduce documentation errors by prompting clinicians to record the required elements at the point of care.

Every +10004 claim requires documentation of these elements:

• Total lesion count and order: A clear statement of how many lesions were sampled and which one is “first” (billed as 10021) versus “additional” (billed as +10004, once per lesion).
• Site and laterality per lesion: The distinct anatomical location of each lesion (e.g., right anterior cervical lymph node, left thyroid lobe), so it’s clear the additional lesion is a separate site, not a repeat pass on the same one.
• Absence of imaging guidance: An explicit statement that every lesion in the session was sampled by palpation only. Silence on this point is not sufficient.
• Needle gauge and technique: Documented per lesion where technique differs, or noted once if consistent across the session.
• Clinical indication per lesion: The medical reason for sampling each lesion, matching the ICD-10 diagnosis code linked to that specific claim line.
• Specimen disposition: Where each specimen was sent (in-house cytology, external pathology lab) and the requested analysis.
• Patient informed consent: Documented consent for the biopsy procedure, per your state’s requirements.

For practices building structured documentation workflows, standardized medical forms across the practice ensure procedure notes capture per-lesion detail consistently, rather than relying on individual clinicians to remember it case by case.

Common billing errors with CPT 10004

Most +10004 denials trace back to the same handful of root causes – and the first one is by far the most common.

How practice management software supports accurate FNA billing

Most FNA billing errors are systemic, not individual. When coders work from incomplete procedure notes, outdated superbills, or charge capture tools that mislabel the primary-plus-add-on relationship, the same error repeats across every claim. Practice management software features address the root cause rather than the individual claim.

Practices using practice management software like Pabau benefit from structured clinical documentation. It captures imaging guidance status and lesion count, per lesion, at the point of care, before the claim reaches the billing team.

The claims workflow then links that documentation to CPT code selection and flags an add-on code submitted without its required primary code, closing the distance between what happened clinically and what gets submitted to the payer.

The add-on pattern isn’t unique to FNA billing. HCPCS code G2211, the visit-complexity add-on for E/M services, works the same way. It can’t be billed without its own primary visit code either.

Reduce FNA add-on billing errors before claims are submitted

Pabau links procedure documentation directly to CPT code selection, flags a missing primary code when an add-on code is billed, and supports NCCI compliance at the point of care – helping billing teams catch errors before claims go out.

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Conclusion

CPT +10004 is easy to misfile if you don’t know what it is: an add-on code for each additional non-image-guided FNA lesion, never a standalone first-lesion code.

The 2019 restructuring deleted 10022, revised 10021 into the current first-lesion code, and created +10004 as its permanent companion.

Getting the claim right comes down to two documentation decisions made before the procedure note leaves the room: was imaging used, and how many lesions were sampled. One rule is easy to forget. +10004 never travels alone.

Pabau’s claims management software connects procedure documentation to CPT code selection at the point of care, so billing teams aren’t reconstructing the clinical picture from incomplete notes. To see how it works for your practice, book a demo.

Continue your research

Wondering what code follows a benign FNA result? D34 is the diagnosis code used once cytology confirms a benign thyroid neoplasm.

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