Thoracic Endodermal Sinus Tumor with Root Compression Mimicking Guillain–Barre Syndrome in Clinical Presentation, CSF Studies, and EMG/NCV Findings

A 2-year-old boy who presented with clinical, cerebrospinal fluid, and electrophysiological findings consistent with Guillain–Barre syndrome (GBS) was found to have a thoracic spinal cord mass due to a yolk sac tumor. On examination, he had an absent anal wink and flaccid anal ring which is atypical for GBS. This case demonstrates the need for a thorough physical examination on presentation of a child with a clinical and laboratory presentation of GBS and highlights the importance of prompt imaging studies when clinical suspicion arises because of atypical clinical signs, such as absent anal wink or low rectal tone.