What is ICD-10 code C83.03?

C83.03 is the ICD-10-CM diagnosis code for Small cell B-cell lymphoma, intra-abdominal lymph nodes. A type of cancer of the lymph system (small cell B-cell lymphoma) affecting the lymph nodes inside the abdominal cavity. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C83.03 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C83.03 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. C83.03 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. C83.03 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.

What is the V28 vs V24 difference for C83.03?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For C83.03, V28 maps to Breast, Prostate, Colorectal and Other Cancers and Tumors at RAF 0.545 while V24 mapped to Lymphoma and Other Cancers at RAF 0.675. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting C83.03?

Confirm documentation specifies intra-abdominal lymph nodes (mesenteric, retroperitoneal, etc.) Review imaging reports (CT abdomen/pelvis) to verify the specific location and extent of lymph node involvement Because C83.03 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

C83.03 ICD-10 Code: Small cell B-cell lymphoma

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupC83.03Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

C83.03

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

Small cell B-cell lymphoma, intra-abdominal lymph nodes

A type of cancer of the lymph system (small cell B-cell lymphoma) affecting the lymph nodes inside the abdominal cavity.

Buddy Insight

Small cell B-cell lymphoma involving intra-abdominal lymph nodes indicates lymphomatous disease in mesenteric, retroperitoneal, or celiac lymph node groups.

CMS-HCC V28

Mapped

HCC 21

Breast, Prostate, Colorectal ...

RAF 0.545

CMS-HCC V24

Mapped

HCC 10

Lymphoma and Other Cancers

RAF 0.675

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 10

Lymphoma and Other Cancers

RAF 0.0

RXHCC

Mapped

HCC 21

Hodgkin Lymphoma and Other Ca...

RAF 0.0

Code Trumping

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Compare selected patient codes to show trumped or trumps impact.

Code Book Path

Official

C83Non-follicular lymphoma

C83.0Small cell B-cell lymphoma

C83.03Small cell B-cell lymphoma, intra-abdominal lymph nodes

Inclusion Terms

Official

Lymphoplasmacytic lymphoma
Nodal marginal zone lymphoma
Non-leukemic variant of B-CLL
Splenic marginal zone lymphoma

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for C83.03 in this effective period.

Related Child Codes

Official

C83.00Small cell B-cell lymphoma, unspecified site

C83.01Small cell B-cell lymphoma, lymph nodes of head, face, and neck

C83.02Small cell B-cell lymphoma, intrathoracic lymph nodes

C83.04Small cell B-cell lymphoma, lymph nodes of axilla and upper limb

C83.05Small cell B-cell lymphoma, lymph nodes of inguinal region and lower limb

Includes

Official

ICD-10-CM does not list Includes notes for C83.03 in this effective period.

Excludes 1

Official

chronic lymphocytic leukemia (C91.1)
mature T/NK-cell lymphomas (C84.-)
Waldenström macroglobulinemia (C88.00)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for C83.03 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for C83.03 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for C83.03 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Pathology-confirmed small cell B-cell lymphoma histology

Specific intra-abdominal lymph node groups identified (mesenteric, retroperitoneal, celiac, para-aortic)

Cross-sectional imaging (CT abdomen/pelvis or PET/CT) confirming abdominal lymph node involvement

Ann Arbor stage documentation

MEAT Support

HCC Buddy guidance

Pathology-confirmed small cell B-cell lymphoma histology

Specific intra-abdominal lymph node groups identified (mesenteric, retroperitoneal, celiac, para-aortic)

Cross-sectional imaging (CT abdomen/pelvis or PET/CT) confirming abdominal lymph node involvement

Ann Arbor stage documentation

Audit Caution

HCC Buddy guidance

Coding splenic involvement as intra-abdominal when spleen has its own specific code C83.07

Using C83.08 (multiple sites) when only abdominal lymph nodes are involved at various levels within the abdomen

Failing to distinguish intra-abdominal lymph nodes from intrapelvic lymph nodes

Common Mistakes

HCC Buddy guidance

C83.06 — Small cell B-cell lymphoma, intrapelvic nodes; differentiate based on anatomical location above vs. below the pelvic brim

C83.09 — Extranodal and solid organ sites; use C83.03 when disease is in abdominal lymph nodes, not solid organs like liver or spleen

C83.07 — Small cell B-cell lymphoma, spleen; spleen is coded separately from intra-abdominal nodes

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is C83.03 an HCC code?

Yes. C83.03 maps to Breast, Prostate, Colorectal and Other Cancers and Tumors under the CMS-HCC V28 risk adjustment model (and Lymphoma and Other Cancers under V24).

HCC Category Mapping

V28HCC 21, Breast, Prostate, Colorectal and Other Cancers and Tumors

0.545

V24HCC 10, Lymphoma and Other Cancers

0.675

ESRDHCC 10, Lymphoma and Other Cancers

0.000

RxHCCHCC 21, Hodgkin Lymphoma and Other Cancers

0.000

RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

MEAT Criteria for C83.03

For C83.03to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

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

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed C83.03 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

C83.03 is the ICD-10-CM diagnosis code for small cell b-cell lymphoma, intra-abdominal lymph nodes. A type of cancer of the lymph system (small cell B-cell lymphoma) affecting the lymph nodes inside the abdominal cavity. C83.03 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, C83.03 maps to Breast, Prostate, Colorectal and Other Cancers and Tumors (HCC 21) with a community, non-dual, aged base RAF weight of 0.545. Under the older CMS-HCC V24 model, C83.03 maps to Lymphoma and Other Cancers (HCC 10) with a community, non-dual, aged base RAF weight of 0.675. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

Confirm documentation specifies intra-abdominal lymph nodes (mesenteric, retroperitoneal, etc.). Because C83.03 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. 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, RAF weights, and MEAT documentation criteria for C83.03 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Confirm documentation specifies intra-abdominal lymph nodes (mesenteric, retroperitoneal, etc.)
•Review imaging reports (CT abdomen/pelvis) to verify the specific location and extent of lymph node involvement

Clinical Significance

Small cell B-cell lymphoma involving intra-abdominal lymph nodes indicates lymphomatous disease in mesenteric, retroperitoneal, or celiac lymph node groups. Abdominal involvement may be associated with gastrointestinal symptoms, bowel obstruction, or organ compression, requiring careful staging to guide therapeutic decisions.

Documentation Requirements

✓Pathology-confirmed small cell B-cell lymphoma histology
✓Specific intra-abdominal lymph node groups identified (mesenteric, retroperitoneal, celiac, para-aortic)
✓Cross-sectional imaging (CT abdomen/pelvis or PET/CT) confirming abdominal lymph node involvement
✓Ann Arbor stage documentation
✓Treatment status and response assessment

Commonly Confused Codes

•C83.06 — Small cell B-cell lymphoma, intrapelvic nodes; differentiate based on anatomical location above vs. below the pelvic brim
•C83.09 — Extranodal and solid organ sites; use C83.03 when disease is in abdominal lymph nodes, not solid organs like liver or spleen
•C83.07 — Small cell B-cell lymphoma, spleen; spleen is coded separately from intra-abdominal nodes