C81.05
BillableNodular lymphocyte predominant Hodgkin lymphoma, lymph nodes of inguinal region and lower limb
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C81.05 an HCC code?
Yes. C81.05 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
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 C81.05
For C81.05 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 C81.05 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C81.05 is the ICD-10-CM diagnosis code for nodular lymphocyte predominant hodgkin lymphoma, lymph nodes of inguinal region and lower limb. A type of Hodgkin lymphoma affecting the lymph nodes in the groin and lower leg area, with nodular lymphocyte-predominant cell patterns. C81.05 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, C81.05 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, C81.05 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.
Ensure documentation specifies inguinal region and/or lower limb involvement to differentiate from other site codes. Because C81.05 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 C81.05 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Ensure documentation specifies inguinal region and/or lower limb involvement to differentiate from other site codes
- •This code includes both inguinal lymph nodes and lower extremity nodes
Clinical Significance
Nodular lymphocyte predominant Hodgkin lymphoma involving inguinal and lower limb lymph nodes is a less common presentation but can be the initial site of disease in some patients. Inguinal lymphadenopathy in NLPHL tends to present as painless groin swelling and requires biopsy to differentiate from reactive lymphadenopathy or other lymphoma subtypes. This peripheral presentation often indicates limited-stage disease with favorable outcomes.
Documentation Requirements
- ✓Pathology confirming NLPHL subtype
- ✓Physical exam and imaging confirming inguinal region and/or lower limb lymph node involvement
- ✓Laterality documented (right, left, or bilateral)
- ✓Assessment for concurrent pelvic lymphadenopathy (which would be coded separately as C81.06)
- ✓Complete staging workup
- ✓Treatment plan
Commonly Confused Codes
- •C81.15 — Nodular sclerosis Hodgkin lymphoma, inguinal/lower limb: Different subtype; requires pathology confirmation
- •C81.06 — NLPHL, intrapelvic lymph nodes: Inguinal nodes are superficial groin nodes; intrapelvic nodes are deep pelvic nodes — anatomically distinct
- •C81.00 — NLPHL, unspecified site: Use C81.05 when inguinal involvement is documented
- •C84.44 — Peripheral T-cell lymphoma, inguinal: Completely different lymphoma type