Extramedullary haematopoiesis secondary to hereditary spherocytosis

Abstract

A 74-year-old woman was urgently referred to haematology. She had initially presented to her general practitioner with breathlessness and weight loss. She was a long-term smoker. A chest X-ray showed a widened mediastinum, and a follow up computerized tomography (CT) scan (left) demonstrated marked thoracic lymphadenopathy and splenomegaly of 19 cm. There were no palpable peripheral lymph nodes. The clinical suspicion was of lymphoma.Her full blood count showed a haemoglobin concentration of 134 g/l, platelet count of 139 · 10 9 /l and normal white count and differential. A blood film demonstrated numerous spherocytes and polychromasia. Lactate dehydrogenase was 212 iu/l (normal: 140-240), bilirubin 99 lmol/l (normal: 2-20) and Coombs test negative. She had a past medical history and family history of hereditary spherocytosis (HS). This was later confirmed by a positive eosin-5maleimide binding test.A bone marrow aspirate and trephine biopsy demonstrated erythroid hyperplasia only. A CT guided biopsy of the mediastinal mass demonstrated extramedullary haematopoiesis (EMH), with no evidence of lymphoma (right). A videoassisted thoracoscopic biopsy similarly showed only EMH.She was negative for the JAK2 V617F mutation. High performance liquid chromatography, for variant haemoglobins and thalassaemia, was normal. A subsequent splenectomy demonstrated a disrupted splenic parenchyma with an increase in the red pulp and no evidence of neoplasia, which would be consistent with splenomegaly secondary to HS.The patient is now symptomatically better, having had a splenectomy to reduce the haemolysis, the presumed driving force for EMH, and also having had her chronic obstructive airways disease managed optimally. A follow-up CT scan 4 months post-splenectomy showed some reduction in the thoracic paravertebral soft tissue mass with increased fat content, suggesting conversion of haematopoietic marrow to fat.This case illustrates how significant posterior mediastinal widening can be due to EMH, which is a rare complication of chronic haemolysis. EMH has been reported in congenital haemolytic anaemias, such as HS, and in thalassaemias, as well as in malignant and myeloproliferative disorders, such as primary myelofibrosis.Case reports of treatment for symptomatic EMH have demonstrated varying success. Treating the underlying cause can reduce the driving force for EMH, resulting in regression of the mass. More immediate benefit can be seen with radiotherapy or surgical resection; however the latter can result in significant bleeding. It must be born in mind that EMH is usually a compensatory mechanism for haemolysis.

Abnormalities of the Erythrocyte Membrane

“…uncommon: chronic leg ulceration, cardiomyopathy, neuromuscular abnormalities, “tumors” due to extramedullary erythropoiesis 32, 33 …”

The Zemblanity of Missing Subtile Changes in the Patient'S Blood Tests-Diagnosing Hereditary Spherocytosis After Finding Extramedullary Haematopoiesis

“…Luckily enough she has never had known anaemia despite giving blood regularly. Extramedullary haematopoiesis is reported as a rare complication of HS [4,5]. One can speculate whether donating blood was the additional stress factor that precipitated the extramedullary haematopoiesis.…”

Extramedullary Hematopoiesis at the Posterior Mediastinum in Patient with Hereditary Spherocytosis: A Case Report

“…As a consequence, patients with hereditary spherocytosis can present with symptoms of anemia, hepatosplenomegaly, jaundice, and venous thromboembolism, and may also present with EMH as a compensatory response [4]. …”