What is ICD-10 code C83.90?

C83.90 is the ICD-10-CM diagnosis code for Non-follicular (diffuse) lymphoma, unspecified, unspecified site. A type of blood cancer (non-follicular lymphoma) where the specific location is not yet identified or documented. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C83.90 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C83.90 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. C83.90 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. C83.90 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does C83.90 map to under V28?

C83.90 maps to CMS-HCC V28 HCC 21 (Lymphoma and Other Cancers). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM C83.90: Non-follicular (diffuse)

C83.90 maps to CMS-HCC V28 21. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software

ICD-10-CM Code View

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Code lookupC83.90

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of lymphoid, hematopoietic and related tissue (C81-C96)

C83.90

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Non-follicular (diffuse) lymphoma, unspecified, unspecified site

A type of blood cancer (non-follicular lymphoma) where the specific location is not yet identified or documented.

Buddy Insight

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 21

Lymphoma and Other Cancers

Code-level coefficient reference

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 010

HHS-HCC 010 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 10

Lymphoma and Other Cancers

Code-level coefficient reference

RXHCC

Mapped

HCC 21

Lymphomas and Other Hematolog...

Code-level coefficient reference

Code Book Path

Official

C83Non-follicular lymphoma C83.9Non-follicular (diffuse) lymphoma, unspecified C83.90Non-follicular (diffuse) lymphoma, unspecified, unspecified site

Inclusion Terms

Official

No inclusion terms are included in this display for C83.90. Check the code and parent instructions in the Code Book.

Excludes 2

Official

Kaposi's sarcoma of lymph nodes (C46.3)Inherited from C81-C96
secondary and unspecified neoplasm of lymph nodes (C77.-)Inherited from C81-C96
secondary neoplasm of bone marrow (C79.52)Inherited from C81-C96
secondary neoplasm of spleen (C78.89)Inherited from C81-C96

Related Codes

Official

C83.91Non-follicular (diffuse) lymphoma, unspecified, lymph nodes of head, face, and neck C83.92Non-follicular (diffuse) lymphoma, unspecified, intrathoracic lymph nodes C83.93Non-follicular (diffuse) lymphoma, unspecified, intra-abdominal lymph nodes C83.94Non-follicular (diffuse) lymphoma, unspecified, lymph nodes of axilla and upper limb C83.95Non-follicular (diffuse) lymphoma, unspecified, lymph nodes of inguinal region and lower limb

Includes

Official

No Includes notes are included in this display for C83.90. Check the code and parent instructions in the Code Book.

Excludes 1

Official

personal history of non-Hodgkin lymphoma (Z85.72)Inherited from C83

Code First

Official

No Code First sequencing instructions are included in this display for C83.90. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for C83.90. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for C83.90. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Pathology report — query for specific non-follicular subtype if only 'lymphoma' or 'non-Hodgkin lymphoma' is documented

Any available imaging to determine site of involvement

Clinical notes supporting the lymphoma diagnosis

Treatment plan or referral to oncology

MEAT Support

HCC Buddy guidance

Pathology report — query for specific non-follicular subtype if only 'lymphoma' or 'non-Hodgkin lymphoma' is documented

Any available imaging to determine site of involvement

Clinical notes supporting the lymphoma diagnosis

Treatment plan or referral to oncology

Audit Caution

HCC Buddy guidance

Accepting this highly unspecified code without querying the provider for more details on subtype and site

Using this code when the medical record actually contains pathology and imaging that would support more specific coding

Not recognizing that 'diffuse lymphoma' in provider notes may correspond to diffuse large B-cell lymphoma (C83.3x) rather than this unspecified category

Failing to review pathology reports that may provide the specific subtype needed for more accurate coding

Common Mistakes

HCC Buddy guidance

C83.80 — Other non-follicular lymphoma, unspecified site: C83.80 indicates the subtype is known as 'other' but site is unspecified; C83.90 has both subtype and site unspecified

C85.90 — Non-Hodgkin lymphoma, unspecified, unspecified site: Even less specific; use C83.90 when at least 'non-follicular' characterization is available

C83.30 — Diffuse large B-cell lymphoma, unspecified site: Use when pathology specifically identifies diffuse large B-cell lymphoma

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is C83.90 an HCC code?

Yes. C83.90 (Non-follicular (diffuse) lymphoma, unspecified, unspecified site) maps to HCC 21, Lymphoma and Other Cancers under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.671. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: C83.90 is billable and maps to V28 HCC 21, Lymphoma and Other Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: C83.90
Description: Non-follicular (diffuse) lymphoma, unspecified, unspecified site
HCC (V28): HCC 21 — Lymphoma and Other Cancers
RAF reference coefficient: 0.671
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 21, Lymphoma and Other Cancers

0.671

ESRDHCC 10, Lymphoma and Other Cancers

Not separately weighted

RxHCCHCC 21, Lymphomas and Other Hematologic Cancers

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work C83.90 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for C83.90

For C83.90, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Coder workflow notes

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What This Code Means

C83.90 is the ICD-10-CM diagnosis code for non-follicular (diffuse) lymphoma, unspecified, unspecified site. A type of blood cancer (non-follicular lymphoma) where the specific location is not yet identified or documented. C83.90 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of lymphoid, hematopoietic and related tissue (c81-c96).

Under the CMS-HCC V28 risk adjustment model, C83.90 maps to Lymphoma and Other Cancers (HCC 21) with a source-labeled community, non-dual, aged reference coefficient of 0.671. No V24 mapping is shown for C83.90; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

This is a less specific code; use only when site of involvement cannot be determined. For C83.90, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for C83.90 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This is a less specific code; use only when site of involvement cannot be determined
•Query provider if additional imaging or pathology results specify the lymphoma location

Clinical Significance

Non-follicular (diffuse) lymphoma, unspecified, at an unspecified site is the least specific code in the non-follicular lymphoma category, indicating both the subtype and anatomic site are unspecified. This code should prompt a query to the provider for more detailed pathology and imaging results. While it still maps to HCC categories, using more specific codes improves documentation quality and audit defensibility.

Documentation Requirements

✓Pathology report — query for specific non-follicular subtype if only 'lymphoma' or 'non-Hodgkin lymphoma' is documented
✓Any available imaging to determine site of involvement
✓Clinical notes supporting the lymphoma diagnosis
✓Treatment plan or referral to oncology
✓Disease status documentation

Commonly Confused Codes

•C83.80: Other non-follicular lymphoma, unspecified site: C83.80 indicates the subtype is known as 'other' but site is unspecified; C83.90 has both subtype and site unspecified
•C85.90: Non-Hodgkin lymphoma, unspecified, unspecified site: Even less specific; use C83.90 when at least 'non-follicular' characterization is available
•C83.30: Diffuse large B-cell lymphoma, unspecified site: Use when pathology specifically identifies diffuse large B-cell lymphoma