Updating single-organ vasculitis

The vasculitic neuropathies: an update

PURPOSE OF REVIEW

Vasculitic neuropathy is a heterogeneous disorder that usually occurs in systemic diseases, but less commonly appears as nonsystemic vasculitic neuropathy (NSVN). This review is intended to highlight recent developments in the field of vasculitic neuropathies.

RECENT FINDINGS

A Peripheral Nerve Society guideline provides data-driven consensus recommendation on classification of vasculitic neuropathies and diagnosis/treatment of NSVN. NSVN is sometimes accompanied by subclinical inflammation of adjacent skin. Amyotrophic lateral sclerosis with sensory involvement can mimic NSVN. Systemic vasculitides with neuropathy include polyarteritis nodosa, microscopic polyangiitis (MPA), rheumatoid vasculitis, Churg-Strauss syndrome (CSS), and hepatitis C-related mixed cryoglobulinemic vasculitis (MCV). At autopsy, MPA affects limb nerves diffusely, with maximal damage in proximal/middle segments. CSS can be accompanied by antineutrophil cytoplasmic antibodies (ANCAs), but most patients with neuropathy lack ANCAs. Cryoglobulinemic neuropathies are usually caused by vasculitis, irrespective of phenotype. Two randomized trials revealed rituximab to be noninferior to cyclophosphamide for inducing remission in ANCA-associated vasculitis. Many reports also document efficacy of rituximab in MCV.

SUMMARY

Consensus guidelines on NSVN should be evaluated prospectively. MPA-associated vasculitic neuropathy results from vasculitic lesions distributed diffusely throughout peripheral extremity nerves. Rituximab is effective for ANCA-associated and cryoglobulinemic vasculitis with neuropathy.

Localized, single-organ vasculitis: clinical presentation and management

The term vasculitis usually evokes a systemic disease with catastrophic outcomes; however, vasculitides may also present in a localized form, with a better prognosis when compared with their systemic counterpart. In order to avoid confusion and facilitate classification, the term single-organ vasculitis (SOV) has been proposed. Remarkably, current criteria for the classification of the vasculitis do not include the SOV term, due in part to the lack of appropriate definitions, since most data come from case series; moreover, the scarce information available is also extremely heterogeneous. This review focuses on the epidemiology, clinical course, prognosis, and suggested treatment of the SOV, with emphasis in the most recent information available.