Korean J Pediatr 2012;55(9):354-357 • http://dx.doi.org/10.3345/kjp.2012.55.9.354 355 Table 1. Diagnostic Criteria for Behçet Disease (International Study Group for Behçet Disease, 1990)3) Recurrent oral aphtae At least three times a year Plus any two of Genital ulcerations Skin lesions Eye involvement Positive pathergy test Active lesion or scar Erythema nodosum, folliculitis, other ulcerations Anterior or posterios uveitis, or retinal vasculitis Skin hyper-reactivity to pinprick (sterile pustule formed in 24 to 48 hr) Neuro-ophthalmologic examination showed impairment of the lateral gaze of the left eye, suggesting damage to left 6th cranial nerve. According to the Medical Research Council grades4), the muscle strength of the left upper and lower extremities is grade 3 and 4, respectively. An initial computed tomography (CT) of the brain showed no abnormalities. Diffuse axonal injury was suspected, and the patient was treated with dexamethasone (5 mg/day), leading to a gradual improvement in his muscle strength but diplopia was static. Although the CT of the brain on admission was normal, T2-weighted and fluid-attenuated inversion-recovery images on the MRI scan which was done in the next day showed abnormal high signal intensity with swelling of the right mesodiencephalic region (Fig. 1). Some kind of venulitis was suggested but there was no cerebral venous thrombosis. The results of white blood cell count, C-reactive protein and urin- alysis were within normal limits. The laboratory studies for C3, C4, rheumatoid factor, anti-nuclear antibodies, anti-neutrophil cytoplasmic antibodies, anti-Ro/La antibodies and HLA B51 revealed all negative findings. We did not exam the cerebrospinal fluid (CSF) analysis because he had no signs of infection in the CNS such as neck stiffness, nausea, vomiting or fever. Despite a negative pathergy test and the absence of typical genital or ocular lesions, the diagnosis of NBD was suggested because of the history of recurrent oral aphthous ulcer, joint pain, and characteristic findings of the brain lesions in the MRI. Subsequently, pulse methylprednisolone was initiated (500 mg/ day for 3 days; 250 mg/day for 3 days; 125 mg/day for 3 days), followed by daily oral prednisolone at 1 mg/kg/day for 28 days. His neurologic status was gradually improved. After 9 days of pulse methylprednisolone therapy, the second MRI scan showed complete improvement of the brain lesion accompanied by an improvement of diplopia and left sided weakness (Fig. 1). During the following 2-month, diplopia or left sided weakness was not recurred. Discussion The diagnosis of BD in children is sometimes difficult because all specific diagnostic manifestations may not be present at the same time and long time intervals may be needed before the appearance Fig. 1. Brain magnetic resonance imaging study of the patient. T2- weighted axial image of the (A) hyperintensity of the right mesodien- cephalic portion and (B) axial fluid attenuated inversion recovery image hyperintensity of the right mesodiencephalic portion obtained 1 day after admission. (C) The follow-up magnetic resonance imaging scan shows no evidence of abnormality after 2 weeks. of characteristic clinical features to make a definite diagnosis5). Since there is no laboratory diagnostic test, the diagnosis of BD depends on essentially clinical findings after the exclusion of other possible diseases. In this case, he had solid neurological manifestations and recurrent history of oral ulceration to be clinically considered NBD. The differential diagnoses include systemic lupus erythematosus (SLE), primary Sjögren syndrome, primary anti-phospholipid antibody syndrome, multiple sclerosis (MS), neurosarcoidosis, viral infections and systemic vasculitis6). Typical autoantibodies suggesting a diagnosis of SLE, primary Sjögren syndrome and primary anti-phospholipid antibody syndrome were absent, and the patient did not fulfill the criteria for SLE or other collagen vascular diseases. The predominant motor system involvement and lack of sensory symptom is a characteristic feature