| M31 | Other necrotizing vasculopathies | NON-BILLABLE CODE |
| M31.0 | Hypersensitivity angiitis | BILLABLE CODE |
| M31.1 | Thrombotic microangiopathy | NON-BILLABLE CODE |
| M31.10 | Thrombotic microangiopathy, unspecified | BILLABLE CODE |
| M31.11 | Hematopoietic stem cell transplantation-associated thrombotic microangiopathy [HSCT-TMA] | BILLABLE CODE |
| M31.19 | Other thrombotic microangiopathy | BILLABLE CODE |
| M31.2 | Lethal midline granuloma | BILLABLE CODE |
| M31.3 | Wegener's granulomatosis | NON-BILLABLE CODE |
| M31.30 | Wegener's granulomatosis without renal involvement | BILLABLE CODE |
| M31.31 | Wegener's granulomatosis with renal involvement | BILLABLE CODE |
| M31.4 | Aortic arch syndrome [Takayasu] | BILLABLE CODE |
| M31.5 | Giant cell arteritis with polymyalgia rheumatica | BILLABLE CODE |
| M31.6 | Other giant cell arteritis | BILLABLE CODE |
| M31.7 | Microscopic polyangiitis | BILLABLE CODE |
| M31.8 | Other specified necrotizing vasculopathies | BILLABLE CODE |
