title: [Extramedullary hematopoiesis in the paravertebral space].
abstract: BACKGROUND
  Extramedullary hematopoiesis is a response of the organism to a deficient production of blood-forming cells within the bone marrow. It may coincide with some hematologic diseases. Two patients with paravertebral mass lesions representing extramedullary hematopoiesis are discussed. Characteristic findings of extramedullary hematopoiesis are presented along with a review of the literature on this topic.
  
  
  METHODS
  A 76-year-old male with a known myelodysplastic syndrome presented with pneumonia. In addition, he had symptoms of a cauda equina syndrome with complaints of pain and hypesthesia of the lower limbs as well as urinary retention. A 63-year-old female presented with aggravated complaints of the lower thorax, low back pain radiating to the upper left leg, and dysesthesia of both feet. In her past medical history, she had polycythemia vera and a splenectomy. Both patients showed paravertebral and intraspinal lesions located in the thoracic and sacral spine which were regarded as extramedullary hematopoiesis according to the imaging findings in MRI and CT. Radiation therapy showed marked improvement in their neurologic complaints following the initial sessions.
  
  
  CONCLUSIONS
  Clinical presentation, knowledge of the underlying disease and of imaging findings are essential in the diagnosis of extramedullary hematopoiesis. MRI is the imaging modality of choice in the primary diagnosis of extramedullary hematopoiesis. Possible extension of the disease into the intraspinal space can be evaluated with high accuracy and differential diagnosis can be facilitated. In addition, MRI is of use in the accurate planning of radiation fields as well as during follow-up of extramedullary hematopoiesis.
authors.affiliation: Zentrum Radiologie, Abteilung Röntgendiagnostik I, Klinikum der Georg-August-Universität Göttingen, Germany. bwraab@med.uni-goettingen.de
authors.forename: Björn-W
authors.initials: BW
authors.lastname: Raab
authors.forename: Henry
authors.initials: H
authors.lastname: Simon
authors.forename: Heinz
authors.initials: H
authors.lastname: Schmidtberger
authors.forename: Uwe
authors.initials: U
authors.lastname: Fischer
authors.forename: Rolf
authors.initials: R
authors.lastname: Vosshenrich
authors.forename: Lorez
authors.initials: L
authors.lastname: Trümper
authors.forename: Eckhardt
authors.initials: E
authors.lastname: Grabbe
mesh_terms: D000368:Aged; D003937:Diagnosis, Differential; D005500:Follow-Up Studies; D006411:Hematopoiesis, Extramedullary / Q000528:radiation effects; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009190:Myelodysplastic Syndromes / Q000150:complications / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000532:radiotherapy; D011087:Polycythemia Vera / Q000150:complications / Q000175:diagnosis; D013902:Radiography, Thoracic; D011879:Radiotherapy Dosage; D013997:Time Factors; D036542:Tomography, Spiral Computed