本態性血小板血症に合併した網膜中心静脈閉塞症の1例

A case of central retinal vein occlusion associated with essential thrombocythemia

　網膜中心静脈閉塞症（うっ血型）をきたした41歳の女性が精査の結果，本態性血小板血症と診断された。赤血球数は正常で，白血球数は軽度増加，血小板数は150.8万／mm³と著しく増加していた。骨髄生検像は，hypercellular marrowで巨核球系細胞の増多やplatelet clumpがみられた。αインターフェロンによる治療の結果，眼底所見は改善した。

　血小板増多に起因する血栓は，網膜血管の閉塞を起こしにくいといわれているが，本症例では慢性関節リウマチが，網膜中心静脈閉塞症の発症に寄与したと考えられる。

A 41-year-old female presented with blurring of vision in the right eye of two months' duration. She had been suffering from rheumatoid arthritis since 2 years before. She was diagnosed as venous stasis retinopathy in the affected eye. Labaoratory studies showed erythrocyte count of 464×10⁴, leu-kocyte count of 14500 and platelet count of 150.8× 10⁴. Bone marrow biopsy showed hypercellularity and megakaryocytes including platelet clumps. The treatment wit α-interferon resulted in lowering the platelet count and improvement in retinal find-ings. The thrombus, which consists of plateletfibrin masses, normally does not cause permanent dam-age to the retina in most cases. The presence of rheumatoid arthritis seems to have contributed to the pathogenesis of central retinal vein occlusion in the present case.