Congenital dyserythropoietic anaemia type II in a teenager presenting with severe anaemia

Abstract

BACKGROUND Congenital dyserythropoietic anaemias (CDAs) are a group of hypoproliferative anaemias characterised by ineffective erythropoiesis.1–4 The most studied variety in this category is CDA type II. The prevalence data of CDA type II is unavailable due to its rarity; however, over 300 cases have been reported in literature. CDAs collectively remain mainly undiagnosed and are often mistaken for other congenital or acquired forms of anaemia.3 4 The diagnosis of CDA is often made in childhood with diagnostic workup done in lieu of reticulocyte counts disproportionate to the anaemia.1–4 CDA type II has an autosomal-recessive mode of inheritance, with congenital defects at the locus of CDAN2 impairing the coded protein SEC23B. This protein has an important role in the assembly of the midbody during cytokinesis.1 Clinical features are variable depending on the degree of ineffective erythropoiesis. Historically, CDA type II has been known by many names: familial benign erythropoietic polyploidy, haemolytic-splenomegalic- erythopolydyskaryosis and hereditary erythroblastic multinuclearity with positive acidified serum lysis test.1 3 As described by its synonyms, virtually all patients with CDA type II have pallor and hepatosplenomegaly with peripheral smear studies showing normocytic anaemia with normal to mildly raised reticulocyte counts.1–4 Diagnosing CDA type II requires a trephine biopsy, which may show binuclearity with erythrocyte hyperplasia in conjunction with laboratory tests ruling out other causes of dyserythropoiesis.1 3 CASE PRESENTATION A female patient in her mid-teens presented as a referral to our emergency department with abdominal distention, pedal oedema and easy fatiguability for the last 2 weeks. Medical history was significant for the diagnosis with β-thalassaemia intermedia when she was an infant, and has since required regular blood transfusions (six packed cell volumes per year prior to current admission). The patient reported that she missed her last four blood transfusions due to financial constraints. The patient belonged to a rural impoverished community. Medical history and laboratory data are mentioned in table 1. The patient was born to a consanguineously married couple (second degree). There was no history of recent deaths or known blood disorders within the family. The patient had a pulse rate of 84 bpm, a blood pressure of 100/60 mm Hg and a temperature of 36.1°C. On examination, the patient had facial puffiness, severe pallor, mild icterus and raised jugular venous pressure. The abdomen was distended, the liver was palpable under the right costal margin and the spleen was located midway between the xiphisternum and the pubic symphysis, and was hard in consistency. With these features of icterus, anaemia and hepatosplenomegaly, a wide differential list including extravascular haemolytic diseases and hepatitis were made. INVESTIGATIONS The patient’s profile was negative for hepatitis antigens and antibodies. Further evaluation was necessary to confirm β-thalassaemia and rule out myelodysplastic syndromes and abdominal tubercular granulomatous bleeding (endemic). The results of the laboratory investigations are as seen in table 2. Radiological investigations including a contrast CT of the abdomen showed massive splenomegaly with regenerative benign liver nodules (figure 1). The bone marrow biopsy showed numerous binucleate erythrocyte precursors (>30% of observed erythroblasts) with binucleation distinctly visualised, by two equal-sized polychromatophilic erythroblasts with equal size nuclei, under H&E stain through multiple sections. Occasional