Diffusion-Weighted Magnetic Resonance Imaging of an Intramedullary Epidermoid Cyst with Dorsal Dermal Sinus Tract in a Toddler

We report the use of diffusion-weighted magnetic resonance imaging to diagnose and manage a rare case of a symptomatic thoracic intramedullary congenital epidermoid cyst with associated dermal sinus in a girl. Congenital intramedullary epidermoid cysts with associated dermal sinuses are very rare occurrences and seldom present symptomatically in very young children. We present a case of a 32-month old with a draining dimpled skin lesion. Magnetic resonance images demonstrated an intramedullary epidermoid with a dorsal dermal sinus tract opening to the skin surface which was confirmed surgically. The patient was treated with debulking to prevent recurrent infection and progression of neurological symptoms. This case demonstrates the use of diffuse-weighted MRI to assist in the diagnosis and surgical management of an atypical presentation of a rare developmental abnormality, which is not well documented in the pediatric radiological literature. Failure to diagnosis may have significant neurological permanent debilitating consequences. 1. Introduction Dermal sinuses are rare abnormalities which result from abnormal cleavage of cutaneous ectoderm from the neuroectoderm. This creates an elongated dermal tube that extends interiorly from the surface and creates a communication from the central nervous system to the skin [1]. The sinus tract may expand to form an epidermoid tumor, a cystic lesion lined by squamous epithelium, which may necessitate surgical removal [2]. Together, spinal epidermoids and dermoids account for approximately 1% of primary spinal tumors. They are more frequent in males. Approximately 60% of epidermoids are intradural extramedullary and 40% are intramedullary. In approximately 5% of cases, there are multiple lesions. An infected dermal sinus may cause abscess formation, or extension from the medulla to the conus medullaris, or a meningeal infection. We report a case of a toddler with an intramedullary epidermoid and dorsal dermal sinus diagnosed with magnetic resonance imaging. The clinical course, pathogenesis, imaging characteristics, and management are discussed. 2. A Case Report A 32-month-old female presented to the emergency department with recurrent upper respiratory infections and fever. History revealed that the patient was born with a dimpled skin lesion on her upper back that was noted to occasionally drain fluid. She was neurologically intact. Physical exam-ination demonstrated several draining pustules on her buttocks. The patient was diagnosed with folliculitis and scheduled for followup with her primary care physician.