A 71-year-old man was referred to a gastroenterological clinic due to macrocytic anemia (hemoglobin 9.9 g/dl, mean corpuscular volume 107 fL) and hyperbilirubinemia (4.4 mg/dL). Haptoglobin was absent (<0.08 g/L) and lactate dehydrogenase was normal (187 U/L). Serum folate levels had previously been low, and the patient was taking iron supplements and folic acid. An ultrasound of the abdomen showed gallstones and splenomegaly. Morphological evaluation of bone marrow biopsy and aspirate showed single-lineage dysplasia (SLD) of >10% of the erythroid precursors, which was found compatible with MDS-SLD if alternative diagnoses such as hemolysis could be excluded. Cytogenetics was not performed.
The patient was referred to a hematological clinic where a CT scan of the chest, neck and abdomen showed a slightly enlarged spleen (13.9 x 6.5 cm). Direct anti globulin test and a flow cytometric direct anti globulin test were both negative and cold agglutinins were not present. Genetic testing for Gilbert's syndrome and pyruvate kinase deficiency as well as flowcytometric testing for paroxysmal nocturnal hemoglobinuria were also negative. Osmotic gradient ektacytometry was initially negative for hereditary spherocytosis (Fig. 1A) and the small pathological erythrocyte population on the EMA-binding test was initially discarded by the laboratory as an artefact (Fig. 1B). A myeloid neoplasm NGS performed on DNA from peripheral blood cells revealed an MDS associated U2AF1 mutation (NM_006758.2: c.470A>G) with an allele burden of 24%. Careful examination of the peripheral blood smear (Fig. 2) revealed numerous spherocytes. This prompted a hemolysis NGS panel which demonstrated a SPTB mutation (NM_001024858.2: c.398T>G), associated with hereditary spherocytosis. The allele burden was 31% at the time of diagnosis and increased to 42% three years later. The SPTB mutation was not found in germline DNA obtained from cultivated fibroblasts. Repeated EMA-binding tests exposed two different erythrocyte populations, whereof one indicated spherocytosis (Fig. 1B). The EMA binding was not reduced for the normal fraction of erythrocytes whereas the pathological population consistently had a decrease of >15% compared to normal controls. The patient was thus diagnosed with acquired spherocytosis, whereas the MDS associated U2AF1 could likely be attributed to clonal hematopoiesis without effect on the patient's hemolytic anemia.
The patient received three units of blood in the setting of surgery and one unit due to chronic fatigue. The patient underwent splenectomy due to persistent anemia with hemoglobin levels around 8.0-9.7 g/dL, need of blood transfusions, and a declining performance status. This resulted in reduced hemolysis with normalization of hemoglobin levels around 13.1 g/dL and bilirubin levels around 2.3 mg/dL (Fig. 1C). Follow-up 2 months after splenectomy showed persistent, close to normalized hemoglobin, and the patient reported substantially improved quality of life.