Department of Radiology, Iran University of Medical Sciences
Hematopoiesis is defined as formation of blood cells from hematopoietic stem cells which reside in the bone marrow. Extramedullary hematopoiesis (EMH) is defined as production of blood cells in other organs in addition to bone marrow. Usual sites of EMH are known to be the spleen and liver, other less common sites of EMH have been reported to be the para spinal region, abdominal viscera, thymus, pleura, and also intracranial structures. Intracranial EMH is a rare condition.
In this article we present a case of intracranial EMH presenting as progressive headache.
Our patient was a 33-year old man with thalassemia presenting with acute progressive flaccid quadriplegia, severe progressive headache and decreased level of consciousness. He had not received his transfusions regularly due to poor compliance. His imaging studies showed evidence of intracranial and pre sacral EMH. Multiple mass-like lesions with a solid and partially dense appearance were seen on both sides of the interhemispheric falx in an extra axial and dural-based position alongside with similar lesions adjacent to the convexity of the right frontal lobe.
Although mostly asymptomatic, intracranial EMH can present as a variety of symptoms including progressive headache. The necessary steps in successful diagnosis of intracranial EMH are considering the patient’s underlying disease, symptoms, and imaging findings. Intracranial EMH has been mostly seen in patients with a history of thalassemia major and intermedia and myelofibrosis. The differential diagnosis should be kept in mind when evaluating a patient with relevant underlying medical condition. Different imaging modalities are used in diagnosis of EMH. The CT appearance of EMH is a heterogeneous lobulated soft tissue density mass. MRI is the modality of choice in the diagnosis of intracranial EMH.