就学時健診を契機に発見された無症候性網膜芽細胞腫の1例

A case of asymptomatic retinoblastoma pointed out by school medical checkup

要約　目的：就学時健診をきっかけに発見された無症状の6歳男児の網膜芽細胞腫の報告。

症例：6歳男児が，就学時健診で左眼の視力低下を指摘され受診した。視力は右1.2（矯正不能），左0.7（1.0×−0.5D）。白色瞳孔および斜視などの自覚症状はなかった。左眼の視神経乳頭上方に10乳頭径大のカリフラワー状の白色隆起性病変が認められた。超音波検査およびCTで腫瘍内石灰化が確認された。網膜芽細胞腫と診断し，左眼眼球摘出術を施行した。病理所見では，前房内，脈絡膜ならびに視神経断端に浸潤はなかった。全身性転移病変も認めなかった。化学療法および放射線療法は併用しなかったが，術後13か月の現在まで再発ならびに転移の所見はない。

結論：就学時健診の視力測定を契機に無症候性の網膜芽細胞腫を診断し，治療することができた。腫瘍の局所再発あるいは全身転移はなく経過している。

Abstract　Purpose：To report a 6-year-old child who was detected to have asymptomatic retinoblastoma during preschool medical checkup.

Case：A 6-year-old boy was referred to us for decreased visual acuity in the left eye detected during pre-school medical checkup.

Findings and Clinical Course：Visual acuity was 1.2 in the right eye without correction, and was 0.7 in the left eye without correction and 1.0 with correction for −0.5 diopter. The left eye showed normal findings in the anterior segment, and profuse vitreous seeding. A white and elevated cauliflower-like mass of about 10 disc diameters across, was present superior to the disc. Ultrasonography and computed tomography（CT）showed calcification within the tumor. The tumor was diagnosed with retinoblastoma and was enucleated. Pathological findings were compatible with well-differentiated retinoblastoma with no invasion into the anterior chamber, choroid, or surgical margin of the optic nerve. No metastasis was detected extraocularly. The patient received no chemotherapy or radiation. He has been doing well for 13 months until present.

Conclusion：Mild visual impairment due to myopia was detected during preschool medical checkup in a 6-year-old child. This finding led to the detection of retinoblastoma and timely treatment.