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Microscopic polyangiitis G042

Last amended 
28 June 2015

Current RMA Instruments:

Reasonable Hypothesis13 of 2011
Balance of Probabilities14 of 2011
Changes from Previous Instruments:

SOP Bulletin 148

ICD Coding:
  • ICD-9-CM Codes: 446.29
  • ICD-10-AM Codes: M31.7

This is a type of vasculitis which is an inflammation of blood vessels. The acute inflammation leads to the death (necrosis) of part of the vessel and is associated with thrombosis. This then leads to scarring of the blood vessel which further can lead to obstruction. This vasculitis only affects arterioles, capillaries and venules.

The clinical manifestations depend upon the organs involved and relate to ischaemia and infarction brought on by the vascular lesions. The organs involved commonly are the kidney with a glomerulonephritis and the lungs.

Is specific diagnostic evidence required to apply the SOP?Yes.

This diagnosis is complex and requires specialist physician opinion based on the histology of the blood vessels. There is no specific specialist physician for this disease with the relevant specialty being related to the site or sites of the vasculitis.

Are there sub-factors that require specific information? – No.

Additional diagnoses covered by SOP
  • Nil
Conditions excluded from SOP
  • Churg-Strauss syndrome (ICD-9 446.4; ICD-10 M30.1)
  • Disseminated necrotising periarteritis (ICD-9 446.0; ICD-10 M30.0)
  • Drug related vasculitis (ICD-9 446.20; ICD-10 M31.0)
  • Giant cell or temporal arteritis (ICD-9 446.5; ICD-10 M31.5)
  • Hypersensitivity vasculitis (ICD-9 446.20; ICD-10 M31.0)
  • Necrotising angiitis (ICD-9 446.0; ICD-10 M30.0)
  • Panarteritis or periarteritis (nodosa) (ICD-9 446.0; ICD-10 M30.0)
  • Polyangiiits overlap syndrome (ICD-9 447.6; ICD-10 M30.8)
  • Polyarteritis with lung involvement (ICD-9 446.4; ICD-10 M30.1)
  • Polyartertitis nodosa (ICD-9 446.0; ICD-10 M30.0)
  • Thromboangiitis obliterans (Buerger’s disease) (ICD-9 443.1; ICD-10 I73.1)
  • Wegner’s granulomatosis (ICD-9 446.4; ICD-10 M31.3)
Unconfirmed diagnosis

If, after applying the above information, you are unable to confirm the diagnosis, you should then seek medical officer advice about further investigation.

The following investigations may be useful in establishing the diagnosis.
  • Histology (biopsy) report