Posterior reversible encephalopathy syndrome as the initial presentation of acute lymphoblastic leukaemia

Posterior reversible encephalopathy syndrome (PRES) is a recognized complication of chemotherapy. However, the development of PRES at presentation of acute lymphoblastic leukemia (ALL) is rare. Here we discuss the uncommon presenting feature of PRES in ALL, and its progression with chemotherapy. A 13-year-old Malay male presented with a one-week history of blurred vision and headache associated with hypertension, hyperkalemia and acute renal failure. CT brain imaging showed symmetrical and bilateral white matter hypodensities at the parietal regions. Brain MRI on T2 and FLAIR images showed patchy areas of high signal intensity at cortical and subcortical region of both parietal and occipital lobes, consistent with PRES. He developed bicytopenia and bone marrow biopsy confirmed pre-B acute lymphoblastic leukemia. He received Phase 1 induction chemotherapy according to the modified UKALL XII protocol but in view of PRES, L-asparaginase and intrathecal methotrexate were delayed until after Day 17 of chemotherapy. No neurological symptoms were observed after chemotherapy. However, during Phase 2 induction chemotherapy with high dose cytarabine and intrathecal methotrexate, he developed accelerated hypertension and status epilepticus requiring mechanical ventilation. Cerebrospinal fluid analysis did not show infection or leukemic infiltration. A repeat brain MRI showed worsening features of the pre-existing PRES, followed by partial resolution on Day 37 of chemotherapy. Subsequent cytotoxic chemotherapies were uneventful except for radiological deterioration of PRES with partial resolution upon hematological recovery. It is important to consider the diagnosis of PRES in a young patient presenting with acute onset of headache and visual disturbances even before the initiation of cytotoxic chemotherapy. In view of the pre-existing PRES, there are risks of further neurological damage and fatal neurological squeal by introducing chemotherapy to treat the leukemia. Therefore it is vital to recognize and treat PRES promptly as early intervention may prevent or reverse the development of encephalopathy.