Rationale:Subacute combined degeneration (SCD) of the spinal cord has been reported to have distinctive characteristics on magnetic resonance imaging (MRI), such as an “inverted V sign”, a “pair of binoculars sign”, and a “dot sign”. We report a 3-point sign as a novel MRI characteristic, expanding the spectrum of imaging signs for SCD.Patient concerns:A 64-year-old female vegetarian presented with a 3-month history of progressive numbness and weakness in the lower extremities.Diagnosis:Laboratory examination showed a reduced serum vitamin B12 level. Spinal MRI showed hyperintensity within the posterior and lateral columns (appearing as a three-point sign) on T2-weighted imaging. Thus, the patient was diagnosed with SCD.Interventions:The patient was treated with intravenous cyanocobalamin and oral vitamin B12.Outcomes:After a follow-up period of 5 months, the symptoms were significantly improved.Lessons:Clinicians should be aware of this atypical MRI pattern, which may facilitate an early diagnosis.