Serological markers of inflammation such as enhanced ESR and C-reactive protein as well as typical CBC changes (leukocytosis, thrombocytosis, anemia) can be missing in all forms of vasculitis.

In PSV one distinguishes between complement-consumpting immune complex vasculitis, ANCA-associated vasculitis and CD4 cell mediated granulomatous vasculitis. For prognostic reasons one should always exclude complicating kidney disease (urine sediment, proteinuria, signs of retention?).

SSV including connective tissue diseases are frequently of immune complex type with polyclonal hypergamma globulinemia. In collagen-vascular diseases, in addition, antinuclear antibodies (ANA) and/or rheumatoid factor is found. Cryoglobulinuria can exist. Complement consumption is seen preferentially from decrease of complement factors C3, C4 and C3d.

The following Figure 62presents a descision tree for initial diagnostic steps in PSV and SSV.

Specific vascular and organ diagnosis is done in the context of establishing activity parameters of the disease. It must be an interdisciplinary approach including bioptical and immunohistological investigation of tissue specimens. For instance, ENT consults are necessary in the diagnosis of Wegener's disease and electromyography (EMG) is suggested in panarteritis nodosa. "Blind biopsies" with a sensitivity of below 30% are usually less helpful in establishing the diagnosis. Kidney biopsies should be taken when pathologic urine sediments and proteinuria are found. It will prove small vessel vasculitis in about 50% of the cases (i.e. segmental necrotizing glomerulonephritis).

In addition, there are several types of reno-pulmonary vasculitides of autoimmune pathogenesis which are not separately described here. The most prominent of these is represented in Goodpasture's syndrome.

Figure 63: pulmonary hemorrhages in a child with Goodpasture's syndrome
Figure 64: renal glomerulitis with arteriolar fibrinoid necrosis
Figure 65: diffuse membranous autoantibody deposits (immunofluorescence)