[Pathogenesis of medium- and large-vessel vasculitis]

Unraveling the Links between Chronic Inflammation, Autoimmunity, and Spontaneous Cervicocranial Arterial Dissection

Advances in imaging techniques have led to a rise in the diagnosis of spontaneous cervicocranial arterial dissection (SCCAD), which is now considered a common cause of stroke in young adults. However, our understanding of the pathophysiological mechanisms underlying SCCAD remains limited. Prior studies have proposed various factors contributing to arterial wall weakness or stress as potential causes for SCCAD. A combination of biopsies, case reports, and case-control studies suggests that inflammatory changes and autoimmunity may play roles in the cascade of events leading to SCCAD. In this review, we examine the close relationship between SCCAD, chronic inflammation, and autoimmune diseases, aiming to explore potential underlying pathophysiological mechanisms connecting these conditions. While some relevant hypotheses and studies exist, direct evidence on this topic is still relatively scarce. Further investigation of the underlying mechanisms in larger clinical cohorts is needed, and the exploration of animal models may provide novel insights.

[Histopathology of systemic vasculitis]

Inflammatory diseases of blood vessels can occur in any part of the vascular system with a variety of clinical and histopathological manifestations. Possible etiologies include primary systemic vasculitis, secondary vasculitis or isolated single organ vasculitis. Key criteria of morphological vasculitis work-up are vessel size, type of inflammation (granulomatous, necrotizing and/or leukocytoclastic) as well as presence or absence of immune complexes and extravascular inflammatory changes. Together with the typical organ involvement and serological data, these criteria constitute the basis of vasculitis classification. A histopathologically confirmed biopsy is the gold standard for a diagnosis of vasculitis, although a definite diagnosis can frequently not be made solely on histopathological grounds. Differential diagnostic overlaps and possible ways of discrimination are presented. In many cases, however, histopathology can only provide a definite diagnosis in combination with clinical and serological data. A conclusive morphological diagnosis depends on the right time of biopsy and selection of appropriate biopsy material.