M31.2 ICD-10-CM Code: Lethal midline granuloma
M31.2 maps to CMS-HCC V28 93. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC Buddy coding tools
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FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Systemic connective tissue disorders (M30-M36)
M31.2
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceLethal midline granuloma
A rare, aggressive cancer-like condition that destroys tissues in the center of the face, including the nose and palate.
Buddy Insight
Lethal midline granuloma is a rare, aggressive lymphoproliferative disorder that primarily affects the nasal cavity and paranasal sinuses with progressive tissue destruction.
CMS-HCC V28
MappedHCC 93
Coefficient HCC 93: 0.617 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 056
Code-level coefficient reference
ESRD/PACE
MappedHCC 40
Code-level coefficient reference
RXHCC
MappedHCC 84
Code-level coefficient reference
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for M31.2. Check the code and parent instructions in the Code Book.
Excludes 2
Official- arthropathic psoriasis (L40.5-)Inherited from M00-M99
- certain conditions originating in the perinatal period (P04-P96)Inherited from M00-M99
- certain infectious and parasitic diseases (A00-B99)Inherited from M00-M99
- compartment syndrome (traumatic) (T79.A-)Inherited from M00-M99
- complications of pregnancy, childbirth and the puerperium (O00-O9A)Inherited from M00-M99
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)Inherited from M00-M99
- endocrine, nutritional and metabolic diseases (E00-E88)Inherited from M00-M99
- injury, poisoning and certain other consequences of external causes (S00-T88)Inherited from M00-M99
- neoplasms (C00-D49)Inherited from M00-M99
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)Inherited from M00-M99
Related Codes
Includes
Official- autoimmune disease NOSInherited from M30-M36
- collagen (vascular) disease NOSInherited from M30-M36
- systemic autoimmune diseaseInherited from M30-M36
- systemic collagen (vascular) diseaseInherited from M30-M36
Excludes 1
Official- autoimmune disease, single organ or single cell-type -code to relevant condition categoryInherited from M30-M36
Code First
OfficialNo Code First sequencing instructions are included in this display for M31.2. Check the code and parent instructions in the Code Book.
Use Additional
OfficialNo Use Additional Code instructions are included in this display for M31.2. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for M31.2. Check the code and parent instructions in the Code Book.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
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 M31.2 an HCC code?
Yes. M31.2 (Lethal midline granuloma) maps to HCC 93, Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.617. 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: M31.2 is billable and maps to V28 HCC 93, Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- M31.2
- Description
- Lethal midline granuloma
- HCC (V28)
- HCC 93 — Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders
- RAF reference coefficient
- 0.617
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
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 M31.2 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for M31.2
For M31.2, 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
M31.2 is the ICD-10-CM diagnosis code for lethal midline granuloma. A rare, aggressive cancer-like condition that destroys tissues in the center of the face, including the nose and palate. M31.2 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering systemic connective tissue disorders (m30-m36).
Under the CMS-HCC V28 risk adjustment model, M31.2 maps to Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders (HCC 93) with a source-labeled community, non-dual, aged reference coefficient of 0.617. 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 serious condition requiring careful documentation of affected sites. For M31.2, 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 M31.2 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This is a serious condition requiring careful documentation of affected sites
- •Distinguish from granulomatosis with polyangiitis (Wegener's) which has different treatment
Clinical Significance
Lethal midline granuloma is a rare, aggressive lymphoproliferative disorder that primarily affects the nasal cavity and paranasal sinuses with progressive tissue destruction. Despite its name, it can be successfully treated with radiation therapy, but early recognition is crucial for optimal outcomes.
Documentation Requirements
- ✓Clinical presentation of destructive midline facial lesions
- ✓Biopsy showing characteristic lymphoid infiltration
- ✓Imaging demonstrating extent of tissue destruction
- ✓Immunohistochemical studies for lymphoma markers
- ✓Staging workup for systemic involvement
- ✓Response to radiation or chemotherapy
- ✓Monitoring for disease progression
- ✓Multidisciplinary oncology team involvement
Commonly Confused Codes
- •C77.0: Secondary and unspecified malignant neoplasm of lymph nodes of head (when lymphomatous)
- •J34.2: Deviated nasal septum (structural nasal problem)
- •M31.30: Wegener's granulomatosis without renal involvement (different granulomatous condition)
- •C30.0: Malignant neoplasm of nasal cavity (primary nasal malignancy)
- •K12.30: Oral mucositis, unspecified (mucosal inflammation only)