Intradural extramedullary metastasis of small cell lung cancer: a case report.

A 60-year-old man presented with para-anesthesia and a tingling sensation in the saddle area. Intradural extramedullary (IDEM) tumors in conus medullaris were observed by radiologic studies. The patient underwent laminoplastic laminotomy at the T12-L2 level and subtotal removal of the tumor because of the ill-defined margin. Postoperatively, hypesthesia was improved up to 50%. The IDEM tumor revealed a metastatic cancer originated from small cell lung cancer (SCLC) by histologic examination, and additional studies showed multiple metastases including adrenal gland, brain, and bone. Clinicians need to consider IDEM metastasis when SCLC patients were complained of neurologic symptoms mimic paraneoplastic syndrome. The pathophysioloigy of IDEM metastasis may be not only tertiary drop metastasis, but also faster mechanisms such as direct invasion.