IntroductionExtradural meningeal cysts, previously called extraduralarachnoid cysts, are relatively rare lesions of the spinal canaland are uncommon causes of spinal cord compression inchildren and adolescents [4, 15]. They are extradural out-pouchings of arachnoid tissue that communicate with theintraspinal subarachnoid space through a small dural defect[5]. According to the classification system by Nabors et al.[16], spinal meningeal cysts are divided into three majorcategories: extradural cysts without spinal nerve root fibers(type I), extradural cyst with spinal nerve root fibers (typeII),andintradural cysts (typeIII).TypeImeningeal cysts arefurther divided into extradural meningeal cysts (type IA)and sacral meningoceles (type IB).The etiology of spinal extradural meningeal cystsremains unclear. Although some can be acquired from trau-ma, infection, or inflammation, the majority of dural defectsare thought to be congenital in nature [3]. In a few reportedcases, authors suggested that a type IA cyst (extraduralmeningeal cyst) may be combined with Scheuermann'sdisease (kyphosis dorsalis juvenilis) [4, 10]. In this report,we present a rare case of spinal cord compressing type IAspinal extradural meningeal cyst with Scheuermann's dis-ease in an adolescent patient.Case reportA 15-year-old male presented with progressive ataxia andgait disturbance for 15 days. In his past history, the patienthad a small head circumference at birth and had surgery forunilateral cryptorchidism. He also showed a developmentaldelay and mental retardation from the age of two. Fifteendays before admission, gait disturbance developed and hehad also progressive difficulty in defecating 3 days beforeadmission.On physical examination, short stature (<3 %), low bodyweight (25–50 %), small head circumference (<30 %), andtic-like movement were noted in the right hand. On neuro-logical examination, he showed grade 4 spastic paraparesisincluding upper motor neuron signs in both lower extremi-ties. His deep tendon reflexes were hyperactive and his gaitwas severely ataxic. Laboratory tests including completeblood count, serum chemistry profile, electrolyte profile,erythrocyte sedimentation rate, C-reactive protein, and rou-tine urinalysis were normal.On radiologic evaluation, plain spinal X-ray and comput-erized tomography revealed irregular narrowing of the discspaces, irregular endplates, and kyphosis, which are consis-tent with Scheuermann's disease. Whole spine magneticresonance imaging (MRI) revealed a dorsally located14.5×7.4×75-mm-sized cerebrospinal fluid (CSF) intensitycystic mass at the T12–L1 level which was noted to extendfrom the epidural space into both neural foramens. Thecystic lesion had low signal intensity on T1-weightedimages, high signal intensity on T2-weighted images, andno contrast enhancement (Fig. 1a, b). His thecal sac andspinal cord were compressed. Also, mild disc bulging on