M31.2 classifies lethal midline granuloma, a rare and destructive necrotizing vasculopathy characterized by progressive inflammation, ulceration, and tissue destruction centered on the midline facial structures — primarily the nose, sinuses, and hard palate.
Verified May 8, 2026 · 4 sources ↓
- Status
- Billable
- Chapter
- 13
- Related CPT
- 0
- Region
- Other
Documentation tips
What should appear in the chart to support M31.2.
Source · Editorial brief grounded in 4 cited references ↓
- Document the specific anatomical sites affected (nose, nasal septum, hard palate, sinuses) to support the midline granuloma diagnosis and distinguish it from other granulomatous conditions.
- Record biopsy results or histopathology findings when available — these are critical for confirming M31.2 versus a more specific diagnosis such as M31.3 (GPA/Wegener's) or an NK/T-cell lymphoma code.
- Note any prior or concurrent diagnostic workup including ANCA testing, imaging of the midline facial structures, and culture results to justify why M31.2 is used rather than a more specific etiology code.
- If the condition is a working diagnosis pending pathology, document it as 'suspected' or 'probable' per standard ICD-10-CM outpatient versus inpatient guidelines — outpatient claims should not code an unconfirmed diagnosis as established.
- Record the clinical history of progression (duration, rate of tissue destruction, prior treatments) to support medical necessity for complex evaluation and management services billed alongside this code.
Common coding pitfalls
The recurring mistakes coders make with M31.2 and adjacent codes.
Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓
- Defaulting to M31.2 when the underlying etiology is already established — if granulomatosis with polyangiitis is confirmed, use M31.3, not M31.2.
- Using M31.2 for any midline facial granuloma without confirming the necrotizing vasculopathy classification — sarcoidosis, fungal granuloma, and cocaine-induced midline destruction each have distinct codes.
- Confusing M31.2 with L92.9 (Granulomatous disorder of skin and subcutaneous tissue, unspecified) — the Diagnosis Index does back-reference 'granuloma gangraenescens' and 'malignant granuloma (facial)' to M31.2, but L92.9 is a skin-specific code and the two are not interchangeable.
- Assigning M31.2 based on symptom presentation alone (epistaxis, nasal obstruction, facial pain) rather than a documented clinical or pathological diagnosis of lethal midline granuloma.
Clinical context
Source · Editorial summary grounded in 4 cited references ↓
M31.2 sits within category M31 (Other necrotizing vasculopathies), itself under the broader section M30–M36 (Systemic connective tissue disorders). Lethal midline granuloma is a historical clinical term encompassing destructive midline facial lesions involving granulomatous inflammation and necrotizing vasculopathy. The condition causes progressive perforation and destruction of nasal, sinus, and palatal structures. Because the underlying etiology (e.g., NK/T-cell lymphoma, Wegener's/GPA, cocaine-induced midline destructive lesion) is often what drives management, confirm with the treating clinician that M31.2 is the intended final diagnosis — not a placeholder pending biopsy results.
This code is most likely to appear in rheumatology, otolaryngology, or oncology crossover cases that land in an orthopedic or connective tissue coding workflow. If the provider has established a specific underlying diagnosis — such as granulomatosis with polyangiitis — M31.3 (Wegener's granulomatosis) or another more specific code is correct. Use M31.2 only when the clinical documentation explicitly supports lethal midline granuloma as the confirmed or working diagnosis, not as a default for unspecified midline facial destruction.
M31.2 has no laterality modifier, no 7th-character extension requirement, and has remained unchanged in every ICD-10-CM edition since its introduction in FY2016. It is a fully billable, specific code with no child codes beneath it.
Sibling codes
Other billable codes under M31 (laterality / anatomic variants).
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 4 cited references ↓
01Is M31.2 the correct code if the provider documents 'midline destructive lesion' without specifying lethal midline granuloma?
02How does M31.2 differ from M31.3 (Wegener's granulomatosis/GPA)?
03Does M31.2 require a 7th character?
04Can M31.2 be used as a primary diagnosis on an outpatient claim when workup is still in progress?
05Are there Excludes1 or Excludes2 notes that affect M31.2 coding?
06What CPT procedures are commonly billed alongside M31.2?
07Has the M31.2 code definition changed in recent ICD-10-CM updates?
Sources & references
Editorial content was developed using the following public sources. Last verified May 8, 2026.
- 01CDC ICD-10-CM Tabular List 2026 (effective October 1, 2025)
- 02icd10data.comhttps://www.icd10data.com/ICD10CM/Codes/M00-M99/M30-M36/M31-/M31.2
- 03aapc.comhttps://www.aapc.com/codes/icd-10-codes/M31.2
- 04cdek.pharmacy.purdue.eduhttps://cdek.pharmacy.purdue.edu/icd10/M31.2/
Mira AI Scribe
The Mira AI Scribe captures anatomical site(s) of destruction (nasal septum, palate, sinuses), histopathology or biopsy status, ANCA and relevant serologic results, and the treating clinician's explicit diagnostic label — distinguishing confirmed lethal midline granuloma from suspected or pending workup. This prevents a claim from going out with M31.2 when a more specific code (M31.3, lymphoma category) is actually supported, which would trigger a payer audit or downcoding.
See how Mira captures M31.2 documentation