Gd-DTPA enhancement in CNS extramedullary hematopoiesis.

Polycythemia vera was diagnosed in a 53-year-old woman who had erythrocytosis , thrombocytosis , and splenomegaly. The patient was treated with phlebotomies for 8 years and then with alkylating agents , and finally splenectomy was performed 14 years after diagnosis because of progressive splenomegaly and refractory thrombocytopenia. Two years later, she had atypical headache for several months, and physical examination showed unsteady gait and mild left ptosis . Histologic examination of a specimen obtained by bone marrow biopsy revealed extensive myelofibrosis with less than 5% myeloblasts. MR with Gd-DTPA showed enhancement of the meninges and focal deposits (Figs. 1 A and 1 B). The extent of disease was not well appreciated on unenhanced MR and was less evident on contrast-enhanced CT. Antimony-sulfur colloid-mTc scintigraphy confirmed the reticuloendothelial nature of the deposits , obviating an invasive biopsy procedure. The diagnosis was meningeal myeloid metaplasia from myelofibrosis caused by polycythemia vera. The patient was treated with low-dose external-beam radiation to the cranium and spine (750 cGy over 5 weeks), which caused complete and stable regression of signs and symptoms. Gd-DTPA-enhanced MR performed after treatment showed subtotal regression of the meningeal deposits (Figs . 1 C and 1 D). To date, none of the neurologic signs and symptoms have recurred .