LAUSR

BACKGROUND Metastatic malignant melanoma of the spine is rare, while the spinal metastatic melanoma with unknown primary lesions presenting as radiculopathy is even rarer. Summarizing and analyzing this disease can provide insight into disease development and allow optimization of clinical management. CASE DESCRIPTION A 55-year-old male patient was admitted to our institution presenting with lower back pain that had persisted for 3 years. It was aggravated, with radiating pain in bilateral lower extremities lasting 2 weeks. Neurologic examination revealed bilateral L5 motor deficit with paresis. The radiological findings showed an irregularly destructive lesion of L5 vertebral body and the lesion extended dorsally, obstructing the spinal canal. The patient underwent complete resection of L5 vertebral tumor with titanium mesh implantation and posterior fusion and instrumentation from L3-S2.The pathological diagnosis after surgery was malignant melanoma. No obvious primary lesion was detected anywhere on the skin surface, mucosa and retina. Postoperative PET-CT scan of the whole body displayed no abnormal uptake in other parts of the body. However, the patient didn't receive any chemotherapy or radiotherapy. 5 months after operation, the tumor recurred and metastasis was detected in other sites. CONCLUSIONS Although spinal metastatic melanoma with unknown primary lesions presenting as radiculopathy is rare, effective management and treatment of these patients remains an important challenge for surgeons. Surgical resection can alleviate patients' chief complaints and improve their quality of life. However, it may not prolong the survival period and improve the prognosis. Postoperative radiotherapy and / or chemotherapy may be needed.