Clinical and Radiological Characteristics of Dorsal Epidural Extrusion of Thoracic Disc Herniation Mimicking Epidural Tumors: 2 Illustrative Cases and a Focused Literature Review.

BACKGROUND: Thoracic disc herniation extruding into the dorsal epidural space is exceptionally rare and is frequently mistaken for an epidural tumor, abscess, or hematoma. We aimed to characterize its clinicoradiological features, identify imaging features that may favor a disc fragment over a neoplasm, and report surgical outcomes. METHODS: We retrospectively present 2 histologically confirmed cases treated by posterior decompression at our institution. To contextualize these cases, a focused literature review was performed, limited to thoracic-only cases, excluding cervical, lumbar, and other epidural pathologies that mimic this condition. The primary outcome (neurological recovery) was prespecified using the modified Frankel grade, with "complete recovery" defined as full motor strength (5/5) plus the patient's preinjury independent ambulation. RESULTS: The pooled cohort comprised 16 patients (14 men, 2 women; median age 56.5 years; T10-T11 most common, 38%). All presented with thoracic myelopathy, most with rapid neurological deterioration. In this highly selected cohort, posterior decompression was followed by neurological improvement in all reported cases, with no major complications. Documented complete recovery was identified in 5 of 16 patients (31%), using a conservative proxy definition, at a median follow-up of 4.5 months (range 0.1-30 months). Contrast enhancement (rim, peripheral, or diffuse) did not reliably distinguish disc fragments from tumor; features favoring a disc fragment were continuity with a degenerated disc space, absence of a dural tail, and absence of a homogeneous markedly high T2 signal. CONCLUSIONS: Dorsal thoracic disc extrusion should be considered when a posterior thoracic epidural mass causes acute or rapidly progressive myelopathy. In the reported thoracic cases, posterior decompression was followed by neurological improvement in all patients, but complete recovery was documented in only 31% under a conservative proxy definition. These findings remain limited by short follow-up, small sample size, level 4 evidence, and significant publication and selection bias. CLINICAL RELEVANCE: A high index of suspicion for dorsal disc extrusion is warranted whenever a posterior thoracic epidural mass is encountered, even when imaging suggests neoplasm. Continuity with a degenerated disc space, absence of a dural tail, and absence of homogeneous markedly high T2 signal are clues that may support early surgical decompression when the clinical presentation is consistent with compressive myelopathy.