Extra-foraminal Intraneural L5-S1 Disc Herniation Mimicking a Retroperitoneal Peripheral Nerve Sheath Tumour: Case Report and Review of the Literature

Disc herniations can present with unusual findings at unusual locations, mimic different pathologies and create confusion in the daily practice. Extra-foraminal intraneural location of L5-S1 disc herniation is extremely rare and may not be noticed on initial imaging extending the time to reach the diagnosis. There is no specific imaging finding suggesting the intraneural location of the lesion. Here, we report a case of an extra-foraminal intraneural L5-S1 disc herniation mimicking a retroperitoneal peripheral nerve sheath tumour and review similar cases in the literature.