Abstract Background: Atypical choroid plexus papilloma (CPP) is an uncommon World Health Organization grade II neuroepithelial intraventricular tumor that can occur in both children and adults. These tumors are usually identified in the fourth ventricle in adults and the lateral ventricles in children. They are rarely found in the spinal cord (synchronous or metastatic). We report the first case of an isolated lumbar grade II atypical CPP. Case description: A 42-year-old man was admitted to the hospital because of back and leg pain. No urinary or rectal dysfunction was detected. Lumbar magnetic resonance imaging (MRI) showed a well-circumscribed, contrast-enhancing, intradural extramedullary mass at L2-3. He underwent L2 and L3 partial laminectomies for tumor resection and complete resection was achieved without causing neurological deficit. Histopathologic examination of the tumor resulted in a diagnosis of grade II atypical CPP. The Ki-67 staining index was 7%. No lesion was detected on postoperative craniospinal MRI. Conclusion: Isolated lumbar atypical CPP in the lumbar region has not been previously reported. In the presence of a single spinal lesion, the diagnosis of CPP should be considered. Unlike metastatic and synchronous tumors, the pathogenesis of isolated choroid plexus tumors within the spinal canal has not been explained.