Background: Differentiation syndrome (DS) is a life-threatening complication that may be seen in patients with acute promyelocytic leukaemia undergoing induction therapy with all-trans retinoic acid or arsenic trioxide. It can lead to severe inflammatory response syndrome and shock if adequate measures are not taken immediately. The radiological features of lung nodules with changes in ground-glass opacity can represent DS. The principal unique feature of the case reported here is that the diagnosis of DS was based on imaging results in the absence of a low total leukocyte count.
Case presentation: A 14-year-old Indian girl diagnosed with acute promyelocytic leukaemia currently undergoing a chemotherapy regimen that included all-trans retinoic acid/arsenic trioxide was sent to the radiology department for investigation of respiratory distress which she had developed soon after the initiation of chemotherapy. Her chest radiograph showed bilateral lower zone lung infiltrates. Computed tomography (CT) revealed changes in ground-glass opacity in the lower lobes with multiple lung nodules. Differential diagnosis included bacterial, viral or fungal infections, leukemic infiltrates, drug toxicity, pulmonary haemorrhage or leukostasis. She was started on dexamethasone immediately after stopping the chemotherapy with all-trans retinoic acid/arsenic trioxide and given ventilatory support. Her condition subsequently improved and her follow-up chest radiograph and CT scan showed a significant reduction of abnormal lung findings. Based on the clinical improvement and the resolution of findings on imaging following the withdrawal of all-trans retinoic acid/arsenic trioxide, we made the diagnosis of DS.
Conclusions: Though a rather unusual possibility, the treatment history of the patient enabled a rather crucial diagnosis in the nick of time and imaging played a pivotal role. This case further iterates the importance of keeping DS in mind when dealing with similar patients in the future.
Keywords: ATO; ATRA; Differentiation; Leukaemia; Lung; Syndrome.