M94.1 identifies relapsing polychondritis — a chronic, acquired inflammatory disease of unknown cause that attacks cartilaginous structures throughout the body, with a characteristic pattern of episodic flares and remissions.

Documentation tips

What should appear in the chart to support M94.1.

Source · Editorial brief grounded in 4 cited references ↓

• Record the specific cartilaginous sites affected (auricular, nasal, costal, tracheal, articular) at each encounter — this supports medical necessity and severity classification for MS-DRG assignment.
• Document the episodic nature of the disease: note whether the encounter represents an active flare or a period of remission, as this informs E/M complexity and supports ongoing management coding.
• If imaging (MRI, CT, or plain films) was used to evaluate joint or cartilage involvement, reference the study and its relevant findings (cartilage loss, calcification, airway narrowing) in the assessment.
• Note any prior or current systemic workup — ANCA, anti-CII antibody, ESR/CRP — that supports the RP diagnosis, since coders and auditors may flag an unusual orthopedic diagnosis without documented clinical reasoning.
• When multiple organ systems are involved, list all confirmed co-diagnoses separately rather than relying on M94.1 alone to capture the full clinical picture.

Related CPT procedures

Procedure codes commonly billed with M94.1. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

Common coding pitfalls

The recurring mistakes coders make with M94.1 and adjacent codes.

Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓

• Assigning a site-specific chondromalacia code (M94.2x) for RP joint involvement — M94.1 is the correct code for the systemic disease regardless of which cartilage sites are active.
• Confusing RP with Tietze syndrome (M94.0): Tietze affects a single costochondral junction and presents with localized swelling; RP involves multiple cartilage sites episodically — they are sibling codes under M94, not interchangeable.
• Omitting secondary diagnosis codes for discrete manifestations (e.g., inflammatory arthritis of a specific joint) when the provider has separately documented and managed those conditions.
• Using a postprocedural chondropathy code (M96.-) after any recent joint surgery when the underlying diagnosis is RP — the M91–M94 block Excludes 1 note bars M96.- from being used alongside M94.1 for the same chondropathy.

Clinical context

Source · Editorial summary grounded in 4 cited references ↓

Sibling codes

Other billable codes under M94 (laterality / anatomic variants).