MRI and clinicopathological correlation of childhood primary central nervous system angiitis

Central and Peripheral Nervous System Complications of Vasculitis Syndromes From Pathology to Bedside: Part 1-Central Nervous System

PURPOSE OF REVIEW

The aim of this review is to provide a comprehensive update on the clinical assessment, diagnosis, complications, and treatment of primary central nervous system vasculitis (PCNSV).

RECENT FINDINGS

The developments in neuroimaging, molecular testing, and cerebral biopsy have enhanced clinical assessment and decision making, providing novel insights to prevent misdiagnosis increasing diagnostic certainty. Advances in imaging techniques visualizing the wall of intracranial vessels have improved the possibility to distinguish inflammatory from non-inflammatory vascular lesions. Large recent studies have revealed a more varied histopathological pictures and disclosed an association with amyloid angiopathy. Unfortunately, therapy remains largely empiric. PCNSV is a heterogeneous group of disorders encompassing different clinical subsets that may differ in terms of prognosis and therapy. Recent evidence has described a more benign course, with good response to therapy. New diagnostic techniques will play soon a pivotal role in the appropriate diagnosis and prompt management of PCNSV.

Clinical Perspective on Primary Angiitis of the Central Nervous System in Childhood (cPACNS)

Non-arteriosclerotic arteriopathies have emerged as important underlying pathomechanism in pediatric arterial ischemic stroke (AIS). The pathogenesis and classification of cerebral arteriopathies in childhood are heterogeneous. Different classifications base on (i) the anatomic site; (ii) the distribution and size of the affected vessel; (iii) the time course, for example, transient vs. progressive, monophasic vs. recurrent; (iv) the putative pathogenesis; (v) the magnetic resonance imaging morphology of the vasculopathies. Inflammation affecting the cerebral vessels is increasingly recognized as common cause of pediatric AIS. Primary cerebral vasculitis or primary angiitis of the central nervous system (CNS) in childhood (cPACNS) is an important differential diagnosis in pediatric AIS. Primary angiitis of the CNS is a rare disorder, and the pathogenesis is poorly understood so far. The current classification of cPACNS is based on the affected cerebral vessel size, the disease course, and angiographic pattern. Two large subtypes are currently recognized comprising large- and medium-sized vessel CNS vasculitis referred to as angiography-positive cPACNS and angiography-negative small vessel cPACNS. As the clinical manifestations of cPACNS are rather diverse, precise diagnosis can be challenging for the treating pediatrician because of the lack of vital laboratory tests or imaging features. Initial misdiagnosis is common because of overlapping phenotypes and pediatric AIS mimics. As untreated cPACNS is associated with a high morbidity and mortality, timely diagnosis, and induction of immunomodulatory and symptomatic therapy are essential. Survival and neurological outcome depend on early diagnosis and prompt therapy. Primary angiitis of the central nervous system in childhood differs in several aspects from primary cerebral angiitis in adults. The aim of this article is to give a brief comprehensive summary on pediatric primary cerebral vasculitis focusing on the clinical perspective regarding the classification, the putative pathogenesis, the disease course, the diagnostic tools, and emerging treatment options. A modified terminology for clinical practice is discussed.

Recent advances in childhood vasculitis

PURPOSE OF REVIEW

The review aims to summarize the recent findings in vasculitis that may have an impact in our understanding or management of these diseases.

RECENT FINDINGS

We are learning more about monogenic diseases that closely mimic the pediatric vasculitides. Deficiency of adenosine deaminase 2 can present with a polyarteritis nodosa (PAN)-like picture and should be included in the differential of all pediatric cases of PAN with a family history or in cases with early stroke, or in cases resistant to conventional therapy. Mutations in tumor necrosis factor α-induced protein 3 results in a disease that can present as Behçet disease called haploinsufficiency of A20. In fact, these patients would also fulfill the existing criteria for PAN and Behçet disease, respectively. Additional advances in Behçet disease pathogenesis come from a large genetic study of Turkish Behçet disease using data obtained from genotyping using the Immunochip. This confirmed the HLA-B-51 locus as the most significant association and identified new risk loci. Large Iranian and Japanese cohorts were used as replication cohorts. Best treatment of pediatric vasculitis remains a challenge as we continue to lack controlled studies. There are new reports in treatment on Henoch-Schönlein purpura/Immunoglobulin A vasculitis which is one of our most frequent childhood vasculitides. Small series of new treatments for central nervous system vasculitis and Takayasu disease will also be summarized. Diagnostic criteria have been reassessed in pediatric Behçet disease as well as adult and childhood forms of antineutrophil cytoplasmic antibodies-positive vasculitis.

SUMMARY

The new pathways defined in monogenic diseases may help us better understand the pathogenesis and may help us design more targeted therapy. Although pediatric cases are being increasingly recognized, the relative rarity of the diseases presents an obstacle for studies. Thus, we can reach conclusive results for their management through multicenter studies only.