Background Spinal dural arteriovenous fistulas (dAVF) remain a rare, diagnostically challenging and possibly correctable condition with important prognostic outcomes dependent primarily on early detection and treatment. Case presentation We present a case of a 73-year-old male with progressively worsening neurological symptoms after steroid administration for a presumed diagnosis of transverse myelitis. This case is extremely unique, as the administration of steroids helped unmask an underlying spinal dural arteriovenous fistula by revealing characteristic imaging findings of a dAVF, not seen on the original MRI study. Conclusion In the setting of an unclear cause of transverse myelitis and worsening symptoms following steroid administration, the possibility of a ‘masked’ dural AVF should be considered and repeat imaging performed, which might help in the eventual diagnosis and definitive treatment of this elusive entity.