Microscopic polyangiitis: Clinical presentation

Utility of immunologic testing in suspected rheumatologic disease

The use of diagnostic testing in the clinical practice of medicine has been a shifting landscape from the time that the first blood test was utilized. This is no different in the field of immunology and in particular rheumatology. As the field of immunology is relatively young, the clinical tests are not well established and therefore guidelines for use are still under debate. In this review, we seek to look at some of the key autoantibodies, as well as other tests that are available to diagnose suspected rheumatologic disease, and examine how to best use these tests in the clinic. In particular, we will focus on the anti-nuclear antibodies, anti-neutrophil cytoplasmic antibodies, complement, cryoglobulins, rheumatoid factor, and anti-citrullinated protein antibodies.

Vasculitic neuropathies

The vasculitic neuropathies are a diverse group of disorders characterised by the acute-to-subacute onset of painful sensory and motor deficits that result from inflammatory destruction of nerve blood vessels and subsequent ischaemic injury. They are common in patients with primary systemic vasculitis and are seen in vasculitis secondary to disorders such as rheumatoid arthritis, viral infections, and diabetic inflammatory neuropathies. It is imperative that neurologists recognise these disorders to initiate treatment promptly and thereby prevent morbidity and mortality. To simplify the approach to patients with vasculitis of the peripheral nerves, a straightforward, dichotomous classification scheme can be used in which the vasculitic neuropathies are divided into two groups-nerve large arteriole vasculitis and nerve microvasculitis-on the basis of the size of the involved vessels. The size of the affected blood vessels correlates with the clinical course and prognosis in patients with vasculitic neuropathy.

Ficolin-1 is up-regulated in leukocytes and glomeruli from microscopic polyangiitis patients

Microscopic polyangiitis (MPA) is a systemic autoimmune disease that often has a fatal outcome. Although delineating the molecular pathogenesis is essential for its remedy, an understanding of its molecular mechanism has remained elusive. To search for new markers of active lesions that might help better understand the molecular basis of MPA and aid in its diagnosis, we here performed DNA microarray analysis with peripheral blood mononuclear cells (PBMCs). Compared to normal control, several genes were up- or down-regulated in MPA patients, including up-regulation of the mRNA level of ficolin-1 (FCN1 or M-ficolin), an innate pattern recognition complement molecule. The amount of ficolin-1, as detected by immunohistochemistry, was higher in the glomeruli of another group of MPA patients than in the glomeruli of control patients who harbored almost normal glomeruli. Many of the ficolin-1 dots were also positive for CD68, suggesting that the ficolin-1-positive cells were monocytes, such as macrophages or dendritic cells. This is not due to the difference in the number of neutrophil or monocytes in the blood samples of MPA and control patients. Taken together, we conclude that increased ficolin-1 expression could serve as a new marker for the characterization of MPA, especially when it is associated with local active lesions.

Microscopic polyangiitis complicated with ileal involvement detected by double-balloon endoscopy: a case report

BACKGROUND

Microscopic polyangiitis is characterized by pauci-immune, necrotizing small-vessel vasculitis and an anti-neutrophil cytoplasmic antibody-associated vasculitis. Although gastrointestinal involvement in microscopic polyangiitis is not rare, endoscopic observation of it is extremely rare. To the best of our knowledge, this is the first case report of small intestinal involvement in microscopic polyangiitis detected and followed up by double-balloon endoscopy.

CASE PRESENTATION

A 70-year-old Japanese woman was transferred to our hospital for close examination of suspected small intestinal lymphoma. Retrograde double-balloon endoscopy revealed various forms of ulcers with redness and edema in the ileum. Histological findings suggested ischemic changes. Because mononeuritis multiplex and a fever spike appeared later, vasculitis was suspected. The perinuclear anti-neutrophil cytoplasmic antibody titer was elevated. Nerve biopsy results suggested vasculitis. From these findings, microscopic polyangiitis was diagnosed. It was suggested that microscopic polyangiitis caused the intestinal involvement. Intravenous pulse cyclophosphamide and oral predonisolone were started. After treatment, perinuclear anti-neutrophil cytoplasmic antibodies decreased to the normal range. Retrograde double-balloon endoscopy after treatment showed ulcer scars and no ulcer.

CONCLUSION

The cause of gastrointestinal involvement in microscopic polyangiitis is ischemia due to vasculitis. It is difficult to diagnose small-vessel vasculitis by endoscopic biopsy. Although histological evidence of microscopic polyangiitis is important, the treatment should not be delayed by repeating the biopsy, because such delay can result in adverse sequela.This case report shows that microscopic polyangiitis should be considered as a differential diagnosis when small intestinal changes like those in the present case are observed by endoscopy.

Renal involvement in anti-neutrophil cytoplasmic autoantibody associated vasculitis

Renal involvement is a common and often severe complication of anti-neutrophil cytoplasmic autoantibody (ANCA) associated vasculitides (AAV). With the exception of Churg-Strauss syndrome (CSS), where kidney involvement is not a prominent feature, renal disease is present in about 70% of patients with Wegener's granulomatosis, now called granulomatosis with polyangiitis (GPA) and in almost 100% of patients with microscopic polyangiitis (MPA). Kidney involvement is generally characterized by a pauci-immune necrotizing and crescentic glomerulonephritis with a very rapid decline of renal function (rapidly progressive glomerulonephritis). Even though there are not qualitative differences in glomerular lesions in patients with GPA or with MPA, chronic damage is significantly higher in MPA (and/or P-ANCA positive patients) than in GPA (and/or C-ANCA positive patients). If untreated necrotizing and crescentic glomerulonephritis has an unfavorable course leading in a few weeks or months to end stage renal disease. Serum creatinine at diagnosis, sclerotic lesions and the number of normal glomeruli at kidney biopsy are the best predictors of renal outcome. Corticosteroids and cyclophosphamide (with the addition of plasma exchange in the most severe cases) are the cornerstone of induction treatment of ANCA-associated renal vasculitis, followed by azathioprine for maintenance. Rituximab is as effective as cyclophosphamide in inducing remission in AAV and probably superior to cyclophosphamide in patients with severe flare, and could be preferred in younger patients in order to preserve fertility and in patients with serious relapses.

Diagnosis and management of pulmonary vasculitis

The pulmonary vasculitides are a heterogeneous group of disorders characterized pathologically by vascular destruction with cellular inflammation and necrosis. These disorders can affect small, medium, and large vessels and may be primary or occur secondary to a variety of conditions. Vasculitis involving the lungs is most commonly due to primary, idiopathic, small-vessel antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides, which includes granulomatosis with polyangiitis (formerly Wegener’s granulomatosis), Churg–Strauss syndrome, and microscopic polyangiitis. From a clinical perspective these remain among the most challenging of diseases both in terms of diagnosis and treatment. This review will focus on diagnosis and management of ANCA-associated vasculitides.

Pulmonary affectation of vasculitis

Respiratory tract affectation is frequent in some types of vasculitis, fundamentally in those associated with anti-neutrophil cytoplasmic antibodies (ANCA). The clinical, radiological and histopathological presentation is also heterogeneous and conditions the evolution. It is therefore necessary to establish an early diagnosis based on the symptoms because, thanks to new treatments, and despite them being potentially serious diseases, their prognosis has improved considerably in recent years. The present paper updates the diagnosis and the new therapeutic options for pulmonary vasculitis.

[Approach and challenges in primary vasculitidies]

The primary systemic vasculitidies (PSV) comprise an heterogeneous group of complex clinical entities with a common substrate: inflammation and necrosis of blood vessels. The inflammatory process involves vessels of any caliber. The location and the different size of the affected vessels, the severity of vascular damage and the different histopathological patterns which may predominate are the basic characteristics that define the different vasculitic syndromes and enable individualization. The description and progress in the knowledge of the primary vasculitidies have evolved considerably in recent decades, allowing for a better resolution of the complex problems placed by these patients. This review aims to provide a view on the practical approach to these diseases and their challenge. It focuses on ANCA associated vasculitidies (AAV) because this subgroup has the only proven biomarker and is the most common in our area. Also, multiorganic involvement is frequent. Some notes regarding other PSV are made.