Mikroskopische Polyangiitis

Microscopic polyangiitis (MPA) is small vessel non-granulomatous necrotizing vasculitis. It most often affects venules, capillaries, arterioles, and small arteries, although it occasionally involves medium-sized arteries.

Epidemiology

It typically affects middle-aged individuals.

Clinical presentation

This condition can affect multiple organ systems. Common sites of involvement are:

  • kidneys: necrotizing glomerulonephritis (present in ~90% of cases )
  • lungs: pulmonary capillaritis
  • skin: purpura
  • gastrointestinal tract 

Pathology

It is histologically very similar to polyarteritis nodosa except for involvement of vessels smaller than arteries (e.g. arterioles, venules, capillaries)

There is an absence or paucity of immunoglobulin localization in vessel walls which distinguishes MPA from immune complex-mediated small vessel vasculitis (e.g. Henoch-Schonlein purpura and cryoglobulinaemic vasculitis)

Markers
  • pANCA-positive in a significant (~70-90%) proportion of cases
Subtypes

Some classify two conditions as organ-specific subsets of this condition :

Radiographic features

Pulmonary involvement

There can be a spectrum of findings which typically include pulmonary hemorrhage:

Other described manifestations (which are non-specific as individual features) include :

Treatment and prognosis

Treatment options in severe forms usually include methylprednisolone +/- cyclophosphamide. Other management options include tumor necrosis factor-alpha blockers rituximab, and nonpharmacologic modalities such as plasmapheresis and ventilatory management .

With treatment, there is often complete remission of the disease in a majority of cases.

Differential diagnosis

The differential can be broad dependent on the type of manifestations and feature.

For lung involvement consider:

History and etymology

It is thought to have been initially described by Friedrich Wohlwill (1881-1958), a German physician, in 1923 .

See also

Siehe auch:
und weiter: