Acute lymphoblastic leukaemia presenting without significant blood count abnormalities: role of medical imaging in two cases

Patient A, a 21‐year‐old man, presented to the emergency department with a 2‐week history of thoracic back pain. This was initially attributed to mechanical injury. He had associated bilateral rib and chest wall pain, as well as low grade fever at 37.8°C. Examination was completely normal. A computed tomography (CT) pulmonary angiogram excluded pulmonary embolus and did not reveal any spinal pathology. His full blood count was unremarkable, with normal white cell count (8.4 × 10⁹/L; reference interval [RI], 4–10 × 10⁹/L) and neutrophil count (6.1 × 10⁹/L; RI, 2–7 × 10⁹/L), slightly reduced haemoglobin 126 g/L (RI for men, 130–170 g/L), and normal platelet count (336 × 10⁹/L; RI, 150–400 × 10⁹/L). C reactive protein (CRP) was elevated at 157 mg/L (RI, < 4.9 mg/L), with elevated lactate dehydrogenase (336 U/L; RI, < 250 U/L). Given his symptoms, fever and elevated CRP, a magnetic resonance imaging (MRI) scan of the spine was performed. This MRI scan revealed diffuse T1 hypointensity and short tau inversion recovery (STIR) hyperintensity throughout the whole spine, consistent with diffuse marrow infiltration, along with multifocal infarcts (bright on STIR), indicating possible leukaemia (Box 1). The blood film showed occasional myeloid precursors, with no circulating blasts seen; however, bone marrow biopsy confirmed acute B‐cell lymphoblastic leukaemia with 86% blasts.