Lots of clots and rods

A 46-year-old male presented at the emergency room with shortness of breath. On physical examination, the 183 cm tall, overweight (body mass index 30 kg/m2) patient with little facial or body hair showed no signs of heart failure. Transcutaneous O2 saturation of 93% and the Knuckle sign on chest X-ray (top left; abrupt tapering of large pulmonary artery; arrow) suggested pulmonary emboli (PE), which were confirmed by computed tomography (CT) scanning (bottom left; arrows). Laboratory evaluation showed cytopenia (Hb 136 g/l, platelet count 87 × 109/l, neutrophil count 0·2 × 109/l, without myeloid precursor cells), significantly increased D-dimer but almost normal prothrombin time/Quick and activated partial thromboplastin time (aPTT): D-dimer 14·6 mg/l (normal <0·5 mg/l), Quick 58% (normal >70%), aPTT 28 s (normal 28–40 s). We decided against thrombolysis, despite echocardiographic signs of right heart failure, and initiated unfractionated heparin at therapeutic doses. A bone marrow aspirate showed abnormal promyelocytes containing multiple Auer rods, so called ‘faggot cells’ (right), a typical finding of acute promyelocytic leukaemia (APL). All-trans-retinoic acid therapy was immediately started. The diagnosis of APL was confirmed by cytogenetic analysis with the detection of the pathognomonic t(15;17) in seven of 10 metaphases. An incidental finding was of an additional X chromosome in all 10 metaphases, suggesting a constitutional aberration compatible with Klinefelter syndrome, which explained the patients' physical appearance. APL is known to induce consumption coagulopathy leading to a haemorrhagic diathesis, the main cause of early mortality in APL. Thromboembolic complications are less commonly observed and are challenging to treat due to the concurrent bleeding risk in APL. Therefore thrombolysis for PE could have been fatal and timely evaluation of the cause of cytopenia was of major importance. Nevertheless, therapeutic anticoagulation had to be established despite the high risk of potentially fatal bleeding due to APL-associated coagulopathy. Klinefelter syndrome has to be regarded as an additional but non-modifiable risk factor for PE even though the mechanism of increased thrombogenesis in this condition is not completely understood.