Spinal Cord Compression Due to Extramedullary Hematopoiesis Associated With Polycythemia Vera. Case Report.

Abstract

A 69-year-old woman with a 14-year history of polycythemia vera suffered progressive paraparesis due to epidural involvement of hematopoietic tissue. Magnetic resonance (MR) imaging demonstrated extensive epidural masses. Decompressive surgery and radiotherapy were performed and she made an almost complete clinical recovery. Serial MR imaging showed no regrowth of the other epidural masses.Extramedullary hematopoiesis occurs in patients with various hematologic disorders involving a chronic increase in the production of red blood cells, and is often associated with thalassemia, but is less common with polycythemia vera. The most frequent sites are the spleen, liver, and kidney. Extramedullary hematopoietic tissue occurring within the spinal canal and causing cord compression is very rare. Total surgical excision is not usually feasible because of the diffuse nature of extramedullary hematopoietic tissue and the possibility of recurrence, but acute neurological deterioration does require emergency surgery. Extramedullary hematopoiesis is radiosensitive and displays a rapid response to low dosages, so radiation therapy is recommended for residual tumors. Considering the possibility of central nervous system extramedullary hematopoiesis in patients with polycythemia vera, an early diagnosis is necessary for a favorable prognosis.

Extramedullary hematopoietic tumor mimicking a thoracic nerve root schwannoma

“…The site at which this occurs is often related to the embryological origin of the tissue: the spleen, liver, and kidney. 2,3,12 Although rare, extramedullary hematopoietic tissue can also occur near the spinal cord. It is hypothesized that the dura mater may retain some ability to form hematopoietic tissue from primitive nests.…”

“…It is hypothesized that the dura mater may retain some ability to form hematopoietic tissue from primitive nests. 3,6,12 Other possibilities are that hematopoietic tissue is extruded from weakened trabeculae in the vertebral bone marrow or that it arises from deposits of circulating immature myeloproliferative cells. 3,7 Schwannomas are often found in patients with neurofibromatosis Type 1 and Type 2.…”

“…Both schwannomas and EMHTs enhance with contrast. 8 On T1-weighted images EMHTs appear isointense with the spinal cord, and on T2-weighted images they appear hypointense, 3 mixed, 10,12 or hyperintense, 6 depending on the inciting condition. One distinctive difference that may help distinguish between the 2 types of lesions is radiographic evidence of bony erosions, which commonly accompany schwannomas.…”

“…1 On the other hand, treatment of EMHTs begins with medical therapies to improve the chronic anemia, such as hydroxyurea, blood transfusions, and intravenous steroids. 3,12 The EMHTs are radiosensitive and respond well to low-dose radiation therapy. 2,3,6,11,12 If the lesion is within the spinal canal and causing significant neural compression, surgical resection my may be necessary despite the increased risk of hemorrhage.…”

Hematopoyesis extramedular: ¿mecanismo compensador o síndrome clínico? Descripción de un caso y revisión bibliográfica

“…Para facilitar la descripción de algunos de estos nosotros preferimos agruparlos en 6 tipos: a) la HEMS que complica el SNC y periférico, uno de los más frecuentes en esta rara patología, que puede presentarse como cefalea intratable (5-7), afectactación cerebelar (8), afasia (7), hemiparesis (7), pérdida del control esfintérico (6,7), otros signos de compresión medular (9-12), una banal ciatalgia (13), un exoftalmo monolateral(7), una hemorragia subdural (14) o paraparesis-paraplejía (6,15); b) la HEMS torácica puede agredir los pulmones y la pleura dando lugar a fibrosis pulmonar (16), derrame pleuritico mono o bilateral (17)(18)(19), hemotórax (20,21) a veces fatales (22), se puede presentar como una masa mediastinal o intratorácica de difícil interpretación (23) o infiltrar el corazón presentándose como precordialgia, disnea cardiaca (24), tamponamiento (24-26) o masa intraatrial (27,28) (la afectación miocárdica en particular la asociación con IMA es al contrario discutible); c) en la HEMS abdominal es frecuente la infiltración peritoneal como ascitis severa (19), incluso refractaria (29) o como un tejido proliferante que determina, en esta últi-ma forma, problemas en el diagnóstico diferencial de la carcinomatosis o del mesotelioma peritoneal (30), cuando su localización es perirenal o retroperitoneal se asocia a cuadros de uropatía obstructiva, infiltración tubulointersticial y urolitiasis, síndrome nefrótico y glomerulonefritis (31,32), insuficiencia renal aguda (33) o puede manifestarse, también aquí, como una masa de dudoso significado (34); d) en la presentación intestinal, además de las hemorragias (35), se reportan casos de estreñimiento importante (36), de oclusión o abdomen agudo quirúrgico (37); e) la HEMS cutánea, de peor pronóstico, puede presentarse sola o acompañando las otras formas (26,38) y es caracterizada por un cuadro heterogéneo: El tratamiento de la HEMS es muy discutido y no existe un acuerdo entre los diferentes autores. En los casos no fatales registrados algunos se resuelven espontaneamente (21), otros con un intenso régimen de trasfusiones (11,12,15), con radioterapia (7,31), cirugía o con combinaciones (47,48) de estos tratamientos según la localización y la modalidad de presentación. La HEM es una patología infrecuente, poco conocida, con frecuencia de tipo compensador a una hemopoyesis medular alterada.…”