Splenic infarction in a patient with sickle cell trait and hereditary spherocytosis

Abstract

A 17-year-old man was presented with severe left upper quadrant abdominal pain shortly after an 8-hr flight from Africa. He was found to have palpable splenomegaly and his initial full blood count showed hemoglobin concentration 11.5 g/dl, mean cell volume 75.6 fl, mean cell hemoglobin 26.2 pg, mean cell hemoglobin concentration 34.6 g/dl, red cell distribution width 23.4% (8.3–17.5%), and platelet count 225 × 109 per liter with a normal white count and differential. Abdominal ultrasonography confirmed splenomegaly (spleen 15.3 cm in length) and showed an echo-poor area in the inferior tip of the spleen. A computed tomography scan showed a 1.5-cm diameter infarct in a considerably enlarged spleen (Image 1, arrow). A thrombophilia screen was normal, no lupus anticoagulant was detected, and a paroxysmal nocturnal hemoglobinuria screen by flow cytometry was negative. Computed tomography scan of the abdomen showing a 1.5-cm focal area of low attenuation in the spleen compatible with infarction. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] As serum ferritin and iron studies were normal, high performance liquid chromatography analysis was performed to investigate the microcytosis; this showed sickle cell trait—hemoglobin A 55.5%, hemoglobin S 38.9%, and hemoglobin F 2.5%. Hemoglobin A2 was not elevated (A2 window 3.1%). Mass spectrometry confirmed hemoglobins A and S as the two major hemoglobins present. A blood film showed microspherocytes and unusual poikilocytes, some boat-shaped, which may have represented partially sickled cells (Image 2). The reticulocyte count was 454 × 109 per liter (28.1–86.1 × 109 per liter), bilirubin 196 μmol/l (0–17 μmol/l), and lactate dehydrogenase 778 iu/l (50–450 iu/l) confirming hemolysis. Dye binding with eosin-5-maleimide was reduced, 0.65 units (0.8–1.2 units) confirming a diagnosis of hereditary spherocytosis. Glucose-6-phosphate dehydrogenase activity was elevated, consistent with the reticulocytosis. Peripheral blood film showing erythrocyte anisopoikilocytosis, microspherocytes, and boat-shaped cells. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.] Although more than 50 cases have been reported, splenic infarction in sickle cell trait is rare. High altitude, with or without vigorous exercise, has been a factor in many reported cases and at least eight have been related to airplane flights. Although the combination of sickle cell trait and hereditary spherocytosis is uncommon, five of 22 reported cases have suffered splenic infarction, sometimes related to flight or high altitude [1-5]. This suggests that splenic infarction is far more likely to occur when these two conditions coexist. The proposed mechanism is slowing of transit of red cells through the spleen because of the spherocytosis, with sickling then occurring in the acidotic and hypoxic environment. Airplane flight or altitude may be the final precipitating factor as in our patient and three previously reported patients [2, 4, 5]. Other patients with coexistence of these two conditions have suffered spontaneous splenic infarction [1, 3]. Coexistence of sickle cell trait and hereditary spherocytosis can also lead to functional hyposplenism with Howell-Jolly bodies, and absent uptake on functional scanning despite a large spleen [6]. Patients with coexistence of these two conditions are similar at risk of splenic sequestration, which may occur during childhood or adolescence rather than being confined to infancy [7]. Splenic infarction has also been reported when sickle cell trait coexists with severe pyruvate kinase deficiency [8], so that patients with sickle cell trait who develop splenic infarction should be investigated not only for hereditary spherocytosis but also for other coexisting red cell disorders. We would like to thank Brian Green who kindly performed the mass spectrometry.