Pediatric T-ALL complicated by irreversible nelarabine neurotoxicity

Nelarabine-induced myelopathy in patients undergoing allogeneic hematopoietic cell transplantation: a report of three cases

Nelarabine is an effective treatment for T-cell acute lymphoblastic leukemia/lymphoma. Myelopathy is a rare but serious adverse event associated with this drug. Three patients who received nelarabine at the National Cancer Center Hospital from December 2014 to March 2021 developed myelopathy 20 days before, 12 days after, and 29 days after allogeneic hematopoietic cell transplantation (allo-HCT), respectively. Magnetic resonance imaging showed that two of the patients had lesions in the dorsal column or medulla oblongata, and one had no abnormalities in the head or spine. Despite treatment with intravenous immunoglobulin and methylprednisolone, all patients became unable to walk. One patient died on day 101 after allo-HCT due to progressive neurotoxicity. The other two patients showed spontaneous improvement in neurological symptoms, but one died of mucormycosis on day 476. Autopsy revealed spongiosis in the posterior funiculus in both patients who died, and also in the medulla oblongata in one patient. In the surviving patient, positron emission tomography on day 84 showed abnormal accumulation, suggesting continued inflammation. These cases demonstrated pathophysiological features of nelarabine-induced myelopathy and indicate that allo-HCT may worsen the condition. It is necessary to elucidate the underlying mechanism and establish diagnostic methods and therapies.

Imaging Findings in Children Presenting with CNS Nelarabine Toxicity

Nelarabine is a nucleoside analog critical for the treatment of patients with T-cell acute lymphoblastic leukemia/lymphoma. However, clinical peripheral and central neurologic adverse events associated with nelarabine administration have been reported. Neuroimaging of brain neurotoxicity has only been described in very few reports in pediatric patients so far. Six children with diagnosed T-cell acute lymphoblastic leukemia who clinically experienced possible, probable, or definite nelarabine-induced toxicity and underwent spine and/or brain MR imaging were reviewed. Neuroimaging findings showed a mixture of patterns including features of acute toxic leukoencephalopathy (seen in 6 cases), posterior reversible encephalopathy syndrome (2 cases), involvement of deep gray structures (1 case) and brainstem (2 cases), cranial and spinal neuropathy (2 cases each), and myelopathy (2 cases). Even though neuroimaging findings are nonspecific, the goal of this article was to alert the pediatric neuroradiologists, radiologists, and clinicians about the possibility of nelarabine-induced neurotoxicity and its broad neuroimaging spectrum.

A case of subacute combined degeneration of the spinal cord due to folic acid and copper deficiency

Subacute combined degeneration of the spinal cord (SACD) is a rare neurologic disorder manifesting progressive symptoms of paresthesia and spastic paralysis. Herein we present an autopsy case of SACD caused by folic acid and copper deficiency. A 16-year-old male presented with gradually worsening unsteady gait, and bladder and rectal dysfunction. He had a medical history of T-cell acute lymphoblastic leukemia (T-ALL), diagnosed 1.5 years previously. The patient had undergone chemotherapy, including methotrexate, as well as allogeneic bone mallow transplantation. Laboratory tests revealed normal vitamin B₁₂ and methylmalonic acid concentration, but reduced serum copper, ceruloplasmin and folic acid concentrations. Magnetic resonance imaging revealed symmetrical T2 signal hyperintensities in the posterior and lateral spinal cord. The patient was treated with oral copper, oral folate, and intravenous vitamin B₁₂. A month after this treatment, the patient's symptoms were unchanged, and 2 months later he died of acute adrenal insufficiency. The pathological findings of the spinal cord were compatible with SACD. Because SACD is usually reversible with early treatment, it should be suspected in high-risk patients undergoing chemotherapy or those who are malnourished with characteristic symptoms of SACD, even in young patients.