A 46-year-old male worker was admitted to the hospital with the symptoms of bilateral lower-limb numbness, lower back pain, and irregular defecation for 5 days. The pain gradually spread to the upper abdomen. Physical examination demonstrated muscle strength of grade 4/5 in lower extremities and grade 5 in upper extremities. There was a presence of hyperalgesia below the T7 level. Muscle tension was normal. Further neurologic examinations revealed normal deep tendon reflexes in arms and legs, as well as normal abdominal reflexes. Pathologic reflexes were also negative on both sides. In addition, the patient had a history of hypertension medication and kidney failure in compensated period. The patient had no history of trauma, cancer, diabetes, or allergic diseases. MRI of the spinal cord demonstrated swelling of the thoracic cord with long-segment diffuse high signal intensity and a heterogeneous nodule with hypointense center at the T7 level on T2-weighted imaging. The post-gadolinium imaging indicated peripheral enhancement of the nodule in the dorsal aspect of spinal cord, while no enhancement of the diffuse high-signal lesion was observed on the T2-weighted images (Figures 1A-D). Brain MRI was normal. Performance of MRI may indicate spinal tumors or inflammatory granuloma such as syphilis, tuberculosis, and neurocysticercosis. Cerebrospinal fluid (CSF) examination showed elevated cell (120/mul, 76% lymphocytes) and protein levels (84 mg/dl), while the levels of glucose and chloride were normal. Syphilis serology including the Treponema pallidum particle agglutination (TPPA) and toluidine red unheated serum test (TRUST) demonstrated positive results. The TRUST titer of serum and CSF were 1/128 and 1/32, respectively. Serological test for HIV was negative. Normal results were observed in the tests for AQP4-IgG, antinuclear antibody, rheumatoid factor, tuberculosis antibody, neurocysticercosis antibody, and tumor marker. The patient denied having a history of venereal diseases and exposure to unprotected intercourse with commercial sexual workers or homosexuality, and also denied any previous symptoms relevant to syphilis infection. There were no skin or mucous lesions or chancre at present. However, given the results of syphilis serologic test, CSF examination, and MRI scan, spinal syphilitic gumma was strongly suspected. The patient was treated with penicillin G (24 million U/day intravenously every 6 h for 14 days) and prednisolone (20 mg/day for 3 days). Three days after the treatment, back pain and bilateral lower-limb numbness were obviously lessened, and irregular defecation was changed correctly. One month after the onset, spinal MRI showed that the lesion was reduced compared with that before the treatment (Figures 2A,B), and the result of the CSF routine test was approaching normal. Serum and CSF TPPA were positive, and TRUST titer of serum and CSF were 1/4 and 1/1, respectively. After 6-month follow-up, the symptoms of pain and numbness disappeared, and CSF studies and spinal MRI demonstrated normal results (Figures 3A,B). A definitive diagnosis of spinal syphilitic gumma was made based on the clinical symptoms, MRI findings, and laboratory tests, as well as with the favorable prognosis after the penicillin therapy.