Hemorrhagic Lumbar Synovial Cyst: Rare Mimic for Mass Lesion Causing Acute Neurological Deficit

BACKGROUND AND IMPORTANCE: Spinal epidural masses are often associated with neoplastic, infectious, or inflammatory etiologies. However, hemorrhagic epidural lesions can mimic these pathologies on imaging, presenting a serious diagnostic challenge. CLINICAL PRESENTATION: This case report presents 2 patients with distinct hemorrhagic epidural masses causing acute bilateral lower extremity weakness. First case is a 63-year-old female presenting with progressive weakness following a cruise, found to have an L3-L5 enhancing epidural mass mimicking an abscess or tumor. Second case is a 55-year-old male with new onset of radiculopathy and weakness, found to have an L4-L5 mass initially suspected to be an intradural tumor. In both instances, advanced imaging was nondiagnostic, and final pathology confirmed benign, hemorrhagic processes: a hemorrhagic synovial cyst in Case 1 and an extradural synovial cyst in Case 2. CONCLUSION: These cases highlight the importance of including hemorrhagic synovial cysts in the differential diagnosis of acute spinal compression, regardless of the patient's oncologic history or atypical presentation. Our findings underscore the importance of timely surgical decompression and definitive histopathological analysis for accurate diagnosis and optimal neurological recovery.