Orbital granulocytic sarcoma成人例の病理学的検討

Histopathological features of orbital granulocytic sarcoma in adult leukemia

　急性骨髄性白血病完全寛解期の45歳男性で，眼窩腫瘍が結膜円蓋部へ突出し，摘出したところOrbital granulocytic sarcoma （OGS）であった。OGSの発症は10歳代がほとんどであり本症例のような高年齢発症は稀で，リンパ系腫瘍との鑑別が重要である。初診より9か月で発症し，腫瘍摘出によって白血病の再発が確認され，6か月後に死亡した。手術中に腫瘍が強膜から比較的容易に剥離できたこと，腫瘍には膠原線維の血管に富んだ偽被膜がみられ，膨張性に腫瘍細胞浸潤がみられたことより発症部位はテノン嚢内が考えられた。OGSと骨髄で，パラフィン標本ではあるがBリンパ球系免疫染色で陽性を示したことにより，特異性には問題があるがBリンパ球系と骨髄系のbiphenotypic leukemjaの可能性があると考えた。

Retinal hemorrhage led to the diagnosis of acute myeloblastic leukemia in a 45-year-old male. Chemotherapy led to apparent complete remission. A small tumor started to develop in the left orbit 9 months after the initial episode. Magnetic resonance imaging showed a well-demarcated tumor inner and superior to the eyeball. The tumor was identified as orbital granulocytic sarcoma after surgical resection. It appeared to be located within the Tenon' s capsule, as it was not adherent to the sclera, was rich in blood vessels, contained pseudocapsular collagenous fibers and expanded by infiltration. There was a possibility of a biphenotypic leukemia of B lymphocytic and myeloid systems. Recurrence of leukemia was detected after surgery and the patient died six months later. The present case merits attention as orbital granulocytic sarcoma typically develops during the second decade of life.