In the classification criteria for childhood vasculitides, Behçet’s disease has been categorized in the “other vasculitides” category [3]. It is a unique vasculitis as, unlike the other systemic vasculitides, it does not have a predilection for vessels of any particular size. Over the years various diagnostic criteria have been proposed which have been detailed in Table 38.1. The International Study Group (ISG) on Behçet’s Disease criteria proposed in 1990 [4] are highly specific but lack sensitivity and accuracy [5]. It was difficult to distinguish inflammatory bowel disease (IBD) from Behçet’s disease using these criteria [6]. The International Criteria for Behçet’s Disease (ICBD) criteria [7] have better sensitivity but are less specific than the previous criteria [5]. Recently, pediatric Behçet’s disease (PEDBD) study had been established, and Kone-Paut et al. have come up with classification criteria for pediatric Behçet’s disease as detailed in Table 38.2 [8].

Though Behçet’s disease is seen globally, it has a high prevalence in areas along the Silk Route, which stretch from the Far East to the Mediterranean countries. It is hypothesized that the genetic risk of the disease has migrated to other areas, consequent to population movement [9]. The prevalence rates in the adults range from as high as 420/100,000 in Turkey and 80/100,000 in Iran to 7.1/100,000 in France, 5.2/100,000 in the USA, and 4.9/100,000 in Sweden [10–14]. The prevalence of pediatric Behçet’s disease in Turkey is around 3.3 % of the total Behçet’s patients, whereas in Iran 5.1 % of the patients began their disease at less than 10 years of age and 25.3 % began in between 10 and 20 years of age [11, 15]. In the pediatric population, female/male ratio ranges from 1.7:1 to 1:1 [15–19]. The onset of Behçet’s disease in adults is most common in the latter half of the second decade of life [11, 20]. In the pediatric literature, the mean age of onset of the disease ranges from 6.9 to 12.2 years of age [15, 17–19, 21].

The etiology of the disease is essentially unknown. It is probably caused by the interplay of genetic, infectious, and immunological factors.

Overlapping features with familial Mediterranean fever and Crohn’s disease also suggest a role of autoinflammation. The carriage of familial Mediterranean fever (MEFV) gene mutation which is responsible for FMF has been found to confer susceptibility to Behçet’s disease [34]. Both these diseases should be carefully differentiated as they share common features such as recurrent bouts of inflammation, high prevalence in the Mediterranean and Middle East countries, and good response to colchicine [35, 36]. Crohn’s disease also shares many of its extraintestinal manifestations with Behçet’s disease such as mucocutaneous lesions, erythema nodosum, and uveitis [35]. Intestinal ulcers are seen in both the conditions and the colonoscopic findings are difficult to distinguish. Round ulcers are more suggestive of Behçet’s disease, whereas longitudinal ulcers are seen in Crohn’s disease [37].

The basic pathology in Behçet’s disease is vasculitis. Skin lesions can show leukocytoclastic or lymphocytic vasculitis, perivascular infiltration, and folliculitis [38]. Helper T cell type 1 inflammatory reaction is seen; however, there is no granuloma formation [39].

Behçet’s disease has diverse clinical presentations with marked regional differences [6]. Table 38.3 summarizes the clinical features seen in various studies across the globe [15–19, 40–43]. A recent observational study showed significant gender differences in the clinical presentations: boys have more ocular and vascular manifestations; girls had more frequent genital aphthae than boys [8]. The clinical symptoms in Behçet’s disease can recur alone or in combinations, over the years. Hence, it has a chronic relapsing course and can be a totally benign disease in some and on the other hand can lead to serious complications.