CASE 10009 Published on 12.04.2012

Imaging in extramedullary haematopoiesis (ECR 2011 Case of the Day)

Section

Chest imaging

Case Type

Clinical Cases

Authors

Lupescu IG, Grasu MC

Fundeni Clinical Institute,
Radiology and Imaging Department,
Bucharest, Romania
Patient

31 years, male

Categories
Area of Interest Education ; Imaging Technique Conventional radiography, CT, MR
Clinical History
A 31-year-old man with a known history of β-thalassemia major, thoracic diffuse pain, dyspnoea, and migraine, was referred to our department for a standard chest evaluation followed by a thoracic and brain CT. After 1 year, a MRI cervico-thoracic spine evaluation was for paresthesia and medullar compression with a thoracic T3-T4 level.
Imaging Findings
Poster-anterior chest radiography (Fig. 1) and lateral chest radiography (Fig. 2) followed by a thoracic CT (Fig. 3-4) and a brain CT (Fig. 5-6) were performed. After 1 year magnetic resonance imaging evaluation of the cervical and the upper part of thoracic spine in sagittal and axial plane T1 weighted was performed (Fig. 7-8). Findings on chest radiographies consists in bilateral, smooth, sharply delineated, lobulated paraspinal masses without erosion of the vertebral bodies or ribs (Fig. 1, 2). Computed tomography of the thorax and head revealed marked medullary expansion of the bony structures with the ribs showing the most pronounced involvement (Fig. 3, 4), but also skull base thickening (Fig. 5, 6). MRI of the spine releved paravertebral and epidural mass with mass effect and compression of the thoracic spinal cord (Fig. 7, 8).
Discussion
Extramedullary haematopoiesis (EMH) occurs as a compensatory mechanism for abnormal haematopoiesis, due to the proliferation of haematopoietic cells outside of the bone marrow in response to production of too few blood cells to satisfy the body's demand [1, 2]. EMH occurs in haemoglobinopathies, myeloproliferative disorders, or bone marrow infiltration. Myeloproliferative disorders include chronic myelogenous leukaemia, polycythemia vera, essential thrombocytosis, and myelofibrosis with myeloid metaplasia. Haemoglobinopathies include sickle cell disease and thalassaemia [3].
EMH mainly involves the RE system (liver, spleen, and lymph nodes) but is also known to occur in every organ of the body, including the thyroid, prostate, pericardium, kidney, and lungs [1]. Rarely, it can cause cord compression, pleural effusion, massive haemothorax, and respiratory failure [3-6]. EMH should be considered in the differential diagnosis in a patient with chronic severe anaemia and a paraspinal mass [6, 7].
Chest radiography reveals a sharply outlined, lobulated paraspinal and rib masses (Fig. 1-2). The thoracic CT examination revealed well-defined bilateral paraspinal and rib masses with intralesional fine linear calcifications (Fig. 3-4). The posterior parts of the ribs showed increased trabeculation and dimensions (Fig. 4). CT of the brain showed a sphenoid osteolytic mass (Fig. 5-6). Conventional spin echo T1 MRI demonstrated that the right paravertebral masses and the mass of the epidural posterior space have the same signal characteristics with the marrow of the adjacent vertebral body (Fig. 7-8). The epidural thoracic mass compress the adjacent thoracic spinal cord (Fig. 8).
Patients with haemoglobinopathies are more likely to have EMH in paraosseous locations, whereas patients with myeloproliferative disorders are more likely to have extraosseous masses [11]. More commonly observed areas of EMH include the paraspinal regions of the thorax, liver, and spleen, but it has been reported in other locations, including the adrenal gland, bowel, dura mater, and breast [11-14]. Only a few cases of perirenal and pelvicaliceal EMH have been reported in the literature [11].
Intrathoracic EMH is a rare cause of paraspinal mass and should be differentiated from other costovertebral angle masses, such as neurogenic tumours, lymphoma, metastasis, paravertebral abscess [1, 8].
EMH usually regresses or disappears after treatment with blood transfusion and hydroxyurea, splenectomy in cases of spherocytosis or radiation therapy [1, 9, 10]. The paraspinal thoracic regions, the spine, and the skull base are common sites of involvements by EMH, and familiarity with its radio-imaging findings and knowledge of the patient's clinical history are essential to avoid misdiagnosis.
Differential Diagnosis List
Extramedullary haematopoiesis
Myeloma
Lymphoma
Multiple ganglioneuroma
Metastasis
Multiple abscesses
Final Diagnosis
Extramedullary haematopoiesis
Case information
URL: https://eurorad.org/case/10009
DOI: 10.1594/EURORAD/CASE.10009
ISSN: 1563-4086