2027 ICD-10-CM Diagnosis Code M31.2Lethal midline granuloma
ICD-10-CM Codes›M00–M99›M30-M36›M31
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 93
- Chronic Condition
M31.2 is a billable ICD-10-CM diagnosis code for lethal midline granuloma. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 542 through 544. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 74 closely related codes. Coders also document this condition as extranodal NK/T-cell lymphoma, nasal type. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Systemic lupus erythematosus and connective tissue disorders and Vasculitis.
For Medicare Advantage risk adjustment, M31.2 maps to CMS-HCC Category 93 (Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders) under the V28 model, adding a risk factor of about 0.617 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
M31.2 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Extranodal NK/T-cell lymphoma, nasal type
- Lethal midline granuloma
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to M31.2: its own notes plus those printed at block M30-M36 and Chapter 13. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- autoimmune disease NOS
- collagen (vascular) disease NOS
- systemic autoimmune disease
- systemic collagen (vascular) disease
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- autoimmune disease, single organ or single cell-type -code to relevant condition category
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- arthropathic psoriasis (L40.5-)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- compartment syndrome (traumatic) (T79.A-)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Notes
General instructions on how these codes are used.
- Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name M31.2, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming M31.2: they are not reported together with it, unless the two conditions are unrelated.
- L94 Other localized connective tissue disorders
Excludes2 4
These codes carry an Excludes2 note naming M31.2: its condition is not part of those codes, and both may be reported when the patient has both.
- Chapter 9 (I00-I99) Diseases of the circulatory system
- I77 Other disorders of arteries and arterioles
- J82 Pulmonary eosinophilia, not elsewhere classified
- Chapter 12 (L00-L99) Diseases of the skin and subcutaneous tissue
Code First 1
These codes say to code first a condition named in the note, and M31.2 is one of the conditions named.
- J84.170 Interstitial lung disease with progressive fibrotic phenotype in diseases classified elsewhere
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
gangraenescens M31.2
malignant (facial (e)) M31.2
midline (lethal) M31.2
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Granuloma, Lethal Midline
a condition that is characterized by inflammation, ulceration, and perforation of the nose and the palate with progressive destruction of midline facial structures. this syndrome can be manifested in several diseases including the nasal type of extranodal nk-t-cell lymphoma and granulomatosis with polyangiitis.
Patient EducationClinical
Head and Neck Cancer
Head and neck cancer is the name for cancers that develop in the mouth, nose and sinuses, salivary glands, and throat and voice box (larynx). Most head and neck cancers are squamous cell cancers. They begin in the moist tissues that line the head and neck. The cancer cells may spread into deeper tissue as the cancer grows.
The full article covers:
- What is head and neck cancer?
- Who is more likely to develop head and neck cancer?
- What are the symptoms of head and neck cancer?
- How is head and neck cancer diagnosed?
- What are the treatments for head and neck cancer?
- Can head and neck cancer be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert M31.2 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About M31.2Overview
What is the ICD-10 code for lethal midline granuloma?
The ICD-10-CM code for lethal midline granuloma is M31.2 (sometimes written as M312). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is M31.2 (Other necrotizing vasculopathies) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report lethal midline granuloma on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does M31.2 group to?
When lethal midline granuloma is the principal diagnosis on an inpatient stay, it groups to MS-DRG 543, 544, 542, with relative weights from 0.7404 to 1.7208 depending on complications. Higher weights mean higher Medicare reimbursement.
Is M31.2 a CC or MCC?
CMS lists M31.2 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 74 closely related codes in its exclusion list.
What is the ICD-9 equivalent of M31.2?
Under the General Equivalence Mappings, lethal midline granuloma converts to ICD-9-CM 446.3 (lethal midline granuloma). The mapping is a direct match.
What HCC is M31.2?
M31.2 (lethal midline granuloma) maps to CMS-HCC Category 93 (Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders), commonly written as HCC 93, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 40 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 84.
Does M31.2 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, M31.2 adds a risk adjustment factor of about 0.617 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.288 to 0.617 depending on the payment segment). HCC 93 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 93 category page.
