Behçet’s disease [29]. Pathergy is tested using the “prick test” in which a 20-g needle is inserted 5 mm obliquely into the skin of the forearm. The test is considered to be positive when sterile erythematous papules or pustules that are a minimum of 2 mm in diameter form 24 to 48 h later. A positive pathergy test is helpful in the diagnosis of Behçet’s disease since there are only a few other rare diseases with pathergy positivity; however, it is not 100% specific or pathognomonic.

Recurrent nonmigrating and nondestructive arthritis episodes, mostly affecting the knees, ankles, wrists, and elbows, occur in approximately half of the patients with Behçet’s disease.

Vascular involvement: Vessels of all sizes in any organ or system can be affected, and the venous system is more commonly affected than the arterial system.

Nervous system involvement usually occurs late in the course of the disease and carries a poor prognosis. Central nervous system involvement is more common than the peripheral. The most common neurologic symptom in Behçet’s disease is headache, which is related to widespread vasculitis [31]. There are a variety of neurologic findings including pyramidal and extrapyramidal signs, cranial nerve palsies, seizures, venous sinus thrombosis, stroke, aseptic meningitis or meningoencephalitis, intracranial hypertension, vertigo, and hearing loss as well as psychiatric disorders [32].

Gastrointestinal system involvement also carries a poor prognosis and presents as single or multiple erosions in any part of the gastrointestinal tract, most commonly at the ileocecal region.

Cardiac system involvement in BD is rare; however, interatrial septum aneurysm, mitral valve prolapse, mitral regurgitation, and aneurysmal dilatations of sinus of Valsalva and ascending aorta are observed in higher incidences in the Behçet’s disease patients than in the normal subjects [33]. Pericarditis, coronary vessel thrombosis, endomyocardial fibrosis, and silent myocardial infarction may also be seen.

Pulmonary involvement includes pulmonary artery aneurysm, pulmonary thromboembolism, infarct, pleural effusion, recurrent pneumonia, and pulmonary hypertension.

The genitourinary system may be affected as epididymitis, cystitis, urethritis, nephrotic syndrome, glomerulonephritis, or renal vein thrombosis.

Ocular Involvement

Behçet’s disease is characterized by recurrent attacks of intraocular inflammation, which resolve over several weeks. Uveitis in Behçet’s disease may be anterior, intermediate, posterior, or panuveitis, which is the most frequent type (around 60%) in both sexes [15]. Although various frequencies of ocular involvement have been reported, it is generally observed in more than 50% of the patients with Behçet’s disease [21]. Ocular manifestations usually follow the onset of oral and genital ulcers by a few years [34]. Ocular involvement is bilateral in the majority of cases but may be asymmetrical. Males are usually more frequently involved, have an earlier disease onset, and have a more severe disease [15, 19].

The uveitis is recurrent and non-granulomatous. Hypopyon, which is composed primarily of neutrophils, is termed as “hot” in the presence of ciliary injection and “cold” with no signs of ciliary injection. Hypopyon (Fig. 12.1), once considered a hallmark of Behçet’s disease, is seen

Fig. 12.1 Iridocyclitis with hypopyon

much less commonly than fundus lesions. It was noted in only 12% of 1,567 eyes [15].

Posterior Segment Involvement

The incidence of posterior segment involvement is reported to be 50–93% [35]. In a study of 880 patients with Behçet’s disease, vitritis and retinal vasculitis were the most common (89%) findings of uveitis [15]. Retinitis, also described as deep retinal exudates, was the second most common finding of Behçet’s uveitis. While hypopyon, vitritis, retinal vasculitis, retinitis, and retinal hemorrhages were more common in male patients, papillitis was more common in females.

Posterior segment examination may show a wide variety of findings:

•Vitreous: Vitritis, haze, hemorrhage, posterior vitreous detachment, pars planitis (Fig. 12.2)

•Retina: Edema, macular edema especially

cystoid type, yellow-white exudates (Fig. 12.3), hemorrhage, retinal neovascularization (Fig. 12.4), chorioretinitis, macular hole (Fig. 12.5), epiretinal membrane, exudative or tractional retinal detachment (Fig. 12.6), retinal pigment epithelial atrophy

•Optic disc: Optic nerve head edema, papilledema (Fig. 12.7), disc neovascularization (Fig. 12.8), optic atrophy (Fig. 12.9)

•Vascular: Venous and capillary dilation, venous tortuosity (Fig. 12.10), sheathing (Fig. 12.11),

Fig. 12.13 Retinal hemorrhages and ghost vessels due to obliterative vasculitis

vasculitis, attenuated arteries, ghost vessels (Fig. 12.12), central or branch retinal vein occlusion, central retinal artery occlusion Obliterative vasculitis (Fig. 12.13), which

affects both arteries and veins, is characteristic in Behçet’s disease leading to retinal edema and retinal exudation. The recurrent nature of this condition leads to severe visual impairment and irreversible alterations in the retina. Episodes of retinal vaso-occlusion may lead to areas of capillary non-perfusion which may result in retinal and/or disc neovascularization. Retinal vascular occlusion has been correlated with three main factors: vascular stasis, throm-

botic abnormalities, and vascular wall abnormalities [29].

The effect of obliterative vasculitis can be detected by color Doppler ultrasonography in patients with Behçet’s disease, which reveals significant reductions in the blood flow values of the orbital arteries that are more evident in those with ocular involvement [36, 37].

Fluorescein Angiography

Fluorescein angiography (FA) contributes greatly to the early diagnosis of the disease and is essential in the long-term care of the patients. Fluorescein leakage from retinal vessels and other signs of vasculitis may be seen before there are obvious ophthalmoscopic signs of vasculitis [35]. Dye leakage from the papillary and retinal capillaries (Fig. 12.14), vascular wall staining (Fig. 12.15), retinal vein and arterial occlusions, cystoid macular edema (Fig. 12.16), vascular remodeling as a result of capillary non-perfusion (Fig. 12.17), and retinal and/or disc neovascularization (Fig. 12.18) are well documented by FA.