The hallmark of Behçet disease is painful aphthous ulcerations in the mouth. These lesions, which usually are multiple, may be found on the tongue, gums, and inner surfaces of the oral cavity (eFigure 20–19). Genital lesions, similar in appearance, are also common but do not occur in all patients. Other cutaneous lesions of Behçet disease include tender, erythematous, papular lesions that resemble erythema nodosum. On biopsy, however, many of these lesions are shown to be secondary to vasculitis rather than septal panniculitis. These erythema nodosum–like lesions have a tendency to ulcerate, which is a major difference between the lesions of Behçet disease and the erythema nodosum seen in sarcoidosis and inflammatory bowel disease. An erythematous follicular rash that occurs frequently on the upper extremities may be a subtle feature of the disease. The pathergy phenomenon is frequently underappreciated (unless the patient is asked); in this phenomenon, sterile pustules develop at sites where needles have been inserted into the skin (eg, for phlebotomy).
Behçet disease. Clinical features include oral and genital ulcers. Ocular features include increased capillary permeability and areas of retinal ischemia and infiltration. Marked leakage of capillaries is seen in the late stages of fluorescein angiography (bottom right). (Reproduced, with permission, from Vaughan DG, Asbury T, Riordan-Eva P [editors]. General Ophthalmology, 15th ed. Originally published by Appleton & Lange. Copyright © 1999 by The McGraw-Hill Companies, Inc.)
A nonerosive arthritis occurs in about two-thirds of patients, most commonly affecting the knees and ankles. Eye involvement may be one of the most devastating complications of Behçet disease. Posterior uveitis, in essence a retinal venulitis, may lead to the insidious destruction of large areas of the retina before the patient becomes aware of visual problems. Anterior uveitis, associated with the triad of photophobia, blurred vision, and a red eye, is intensely symptomatic. This complication may lead to a hypopyon, the accumulation of pus in the anterior chamber. If not treated properly with mydriatic agents to dilate the pupil and corticosteroid eyedrops to diminish inflammation, the anterior uveitis may lead to synechial formation between the iris and lens, resulting in permanent pupillary distortion.
Central nervous system involvement is another cause of major morbidity in Bechet disease. Findings include sterile meningitis (recurrent meningeal headaches associated with a lymphocytic pleocytosis), cranial nerve palsies, seizures, encephalitis, mental disturbances, and spinal cord lesions. The central nervous system lesions may mimic multiple sclerosis radiologically. Aphthous ulcerations of the ileum and cecum and other forms of gastrointestinal involvement develop in approximately a quarter of patients. Large vessel vasculitis can lead to pulmonary artery aneurysms and life-threatening pulmonary hemorrhage. Finally, patients have a hypercoagulable tendency that may lead to complicated venous thrombotic events, particularly multiple deep venous thrombosis, pulmonary emboli, cerebral sinus thrombosis, and other problems associated with clotting.
The clinical course may be chronic but is often characterized by remissions and exacerbations.
There are no pathognomonic laboratory features of Behçet disease. Although acute-phase reactants are often elevated, there is no autoantibody or other assay that is distinctive. No markers of hypercoagulability specific to Behçet have been identified. Behçet disease is known to have a genetic risk factor (HLA B51), but this gene is neither necessary nor sufficient to cause the disease.