NTCT-04: SPINAL CORD TOXICITY FROM INTRATHECAL CHEMOTHERAPY: A CASE WITH CLINICOPATHOLOGIC CORRELATION

We report antemortem pathologic and neuroimaging findings of severe myelotoxicity from intrathecal chemotherapy in a case of blastic plasmacytoid dendritic cell neoplasm (BPDCN) complicated by leptomeningeal disease. A 73 year old male was diagnosed with BPDCN after fine needle aspiration of an enlarged cervical lymph node. Total body PET imaging revealed extensive systemic hypermetabolic lymphadenopathy and a staging lumbar puncture was positive for malignant cells. He was treated with etoposide, vincristine, doxorubicin, cyclophosphamide, prednisone (EPOCH) and five doses of intrathecal cytosine arabinoside with the last dose administered on 2 months after diagnosis with CSF clearing. One year later, he developed progressive lower extremity weakness, numbness and bowel/bladder dysfunction. Lumbar spine imaging 4 weeks later revealed subtle linear enhancement along the cauda equina and within the dependent thecal sac, but cervical and thoracic spine MRI at this time were unremarkable. CSF showed atypical lymphoid cells and an Ommaya reservoir was placed. Intrathecal chemotherapy with methotrexate and cytarabine was started. Subsequent CSF analysis showed no malignant cells. However, the patient continued to have progressive ascending weakness and numbness, and his neurologic condition progressed to tetraplegia, low of bowel and bladder control and severe sensory loss, especially to vibration and joint position modalities. Spine MRI showed high signal intensity involving the posterior columns diffusely in the cervico-thoracic spinal cord. Metabolic and infectious work up was negative. A subsequent biopsy of the posterior columns of the lower thoracic spinal cord demonstrated cord destruction with profuse macrophage infiltration without evidence of malignant cells or microorganisms. Treatment with folate and cyanocobalamin resulted in no improvement, and the patient elected for palliative care only. This case illustrates central nervous system involvement by a rare myeloid tumor and demonstrates neuroimaging and unique antemortem pathology of intrathecal chemotherapy-induced myelotoxicity.