C84.73
BillableAnaplastic large cell lymphoma, ALK-negative, intra-abdominal lymph nodes
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C84.73 an HCC code?
Yes. C84.73 maps to Lymphoma and Other Cancers under the CMS-HCC V28 risk adjustment model (and Lymphoma and Other Cancers under V24).
HCC Category Mapping
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 C84.73
For C84.73 to 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 C84.73 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C84.73 is the ICD-10-CM diagnosis code for anaplastic large cell lymphoma, alk-negative, intra-abdominal lymph nodes. A type of aggressive lymphoma (cancer of immune cells) without a specific genetic marker (ALK-negative) that is located in the lymph nodes within the abdominal cavity. C84.73 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, C84.73 maps to Lymphoma and Other Cancers (HCC 19) with a community, non-dual, aged base RAF weight of 0.105. Under the older V24 model, C84.73 mapped to the same category but with a base RAF weight of 0.675 — V28 recalibrated weights across the entire model. 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.
Verify specific abdominal lymph node involvement (mesenteric, retroperitoneal, etc.) through imaging or pathology reports. Because C84.73 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 C84.73 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify specific abdominal lymph node involvement (mesenteric, retroperitoneal, etc.) through imaging or pathology reports
- •Distinguish from splenic involvement, which has a separate code (C84.77)
Clinical Significance
Anaplastic large cell lymphoma, ALK-negative, involving intra-abdominal lymph nodes indicates aggressive T-cell lymphoma without the ALK marker affecting abdominal nodal basins. Abdominal ALCL may present with nonspecific symptoms such as pain, bloating, or weight loss. The worse prognosis of ALK-negative disease necessitates aggressive multiagent chemotherapy.
Documentation Requirements
- ✓Pathology confirming ALCL with ALK-negative status
- ✓Abdominal imaging documenting specific lymph node groups involved
- ✓CD30 positivity and T-cell markers on immunohistochemistry
- ✓Distinction from hepatosplenic T-cell lymphoma and enteropathy-associated T-cell lymphoma
- ✓Clinical staging documentation
Commonly Confused Codes
- •C84.63 — ALCL ALK-positive, intra-abdominal: Different ALK status
- •C84.43 — PTCL-NOS, intra-abdominal: Different subtype
- •C84.76 — ALCL ALK-negative, intrapelvic: Pelvic nodes are below pelvic brim; distinguish from abdominal
- •C84.77 — ALCL ALK-negative, spleen: Spleen has its own code; not an abdominal lymph node