C90.32
BillableSolitary plasmacytoma in relapse
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C90.32 an HCC code?
Yes. C90.32 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 C90.32
For C90.32 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 C90.32 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C90.32 is the ICD-10-CM diagnosis code for solitary plasmacytoma in relapse. A single tumor made of plasma cells that has returned after a period of remission. C90.32 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, C90.32 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, C90.32 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.
Relapse means the cancer has recurred; ensure documentation supports this status rather than initial diagnosis. Because C90.32 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 C90.32 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Relapse means the cancer has recurred; ensure documentation supports this status rather than initial diagnosis
- •Distinguish between relapse and progression during ongoing treatment
Clinical Significance
Solitary plasmacytoma in relapse indicates recurrence of the bone lesion after achieving remission, which may occur at the original site or as a new solitary bone lesion. Relapse is a critical juncture as it significantly increases the likelihood of progression to systemic multiple myeloma. Comprehensive restaging is essential to determine whether the disease remains solitary or has evolved into multiple myeloma.
Documentation Requirements
- ✓Documentation must show evidence of recurrence after documented remission, with imaging confirming the relapsed lesion.
- ✓Complete restaging including bone marrow biopsy, skeletal survey or PET-CT, and serum and urine protein studies must be performed to exclude myeloma evolution.
- ✓New treatment plan and disease burden assessment must be recorded.
Commonly Confused Codes
- •C90.30 (solitary plasmacytoma not in remission) is for initial non-response.
- •C90.31 (solitary plasmacytoma in remission) indicates no recurrence.
- •C90.02 (multiple myeloma in relapse) should be used if restaging reveals systemic disease.
- •C90.20 (extramedullary plasmacytoma) applies to soft tissue relapse.