Isolated Large Lateral Thoracic Meningocele.

Intrathoracic meningocele is a condition characterized by the protrusion of dura mater and cerebrospinal fluid within the thoracic cavity. This can be associated with neurofibromatosis type 1 (NF1) and other connective tissue disorders. Less commonly, it can occur in isolation. We describe one of the few cases of a large thoracic meningocele presenting in an adult without NF1 or another genetically predisposing condition. This case involves a 78-year-old woman who presented with back pain, shortness of breath, and lower limb weakness. The computed tomography (CT) scan reported a pleural effusion, with plans made to drain the fluid. However, magnetic resonance imaging (MRI) revealed a large right-sided lateral thoracic meningocele. This case highlights the diagnostic challenges and potential complications associated with the misdiagnosis of thoracic meningoceles. It also reaffirms MRI as the gold standard for diagnosis.