Vasculitides with cutaneous expression in children: clinico-pathological correlations

The most recent pediatric vasculitis classifications (EULAR/PRINTO/PRES) have proposed the use of an integration of clinical signs and symptoms, laboratory data, imaging and pathologic data. Pediatric vasculitis represent a peculiar clinical-diagnostic model, compared to the corresponding adult pathology chapter, and in particular, dermatopathologic aspects of these diseases identify more specific issues, made contingent by crucial variables such as duration of vasculitis lesion, site of the biopsy, proper biopsy depth, and possibility to correlate histopathological findings with immunopathological results. Possible additional diagnostic difficulties may arise from the fact that, in children, the same systemic disease, such as lupus erythematosus, may present with different clinical manifestations, with histopathological features of a precise type of vasculitis specific for that type of clinical manifestation. Examples are provided by hypocomplementemic urticarial vasculitis, cryoglobulinemic purpura, lymphocytic vasculitis of livedoid lesions. This paper describes the cutaneous histopathological findings of some vasculitis related pediatric diseases, be they pertaining to a systemic vasculitis with corresponding cutaneous vasculitis, to a systemic vasculitis with sporadic cutaneous vasculitic involvement, and to a systemic vasculitis without cutaneous vasculitic involvement. Type and level of histopathological vasculitic involvement, caliber of the vessel, type of vasculitis associated infiltrate, are likewise reliable integration in the complex diagnostic path of vasculitis in childhood. On the basis of these criteria dermatopathologists should be confident in identifying the type of the vasculitis and relate them to a specific pediatric disease.