当初甲状腺眼症が疑われた眼付属器MALTリンパ腫の1例

A case of MALT lymphoma in the ocular adnexa initially suspected of thyroid-associated ophthalmopathy

要約　目的：当初は甲状腺眼症が疑われ，いったん軽快した後に再発し，最終的にMALTリンパ腫の診断が確定した症例の報告。

症例：52歳の女性が左眼の眼球突出と複視で受診した。MRIで外眼筋の肥厚があり，甲状腺関連の自己抗体が陽性であったために，甲状腺眼症と診断した。ステロイドパルス療法で症状は軽快した。初診から約26か月後に左眼の視力が低下し，甲状腺視神経症と診断してステロイドパルス療法と放射線照射を行い，視力は改善した。その約5年後に両側の涙腺が腫脹した。生検でCD20陽性の異型細胞増殖があり，MALTリンパ腫が強く疑われた。リツキシマブとベンダムスチンの全身投与を行い，眼瞼腫脹は軽快した。

結論：本症例では，甲状腺眼症による慢性炎症が，MALTリンパ腫が発症する基盤となった可能性がある。診断の確定には生検が有用であった。

Abstract　Purpose：To report a case who was initially suspected of thyroid-associated ophthalmopathy and who was ultimately diagnosed as mucosa-associated lymphoid tissue（MALT）lymphoma following treatment and remissions.

Case：A 52-year-old woman was referred to us with diplopia and protrusion of the left eye as chief complaints.

Findings and Clinical Course：Magnetic resonance imaging（MRI）showed thickening of extraocular muscles. She was positive for anti-thyroid autoantibodies. The findings led to the tentative diagnosis of thyroid-associated ophthalmopathy. The symptoms subsided after pulsed corticosteroid therapy. She developed impaired visual acuity in the left eye 26 months later and was diagnosed with rhyroid optic neuropathy. Visual acuity improved following pulsed corticosteroid and radiation. She developed pronounced swelling of bilateral lacrimal glands. Biopsy showed proliferation of CD-positive atypical cells, suggesting MALT lymphoma. Eyelid swelling subsided following systematic treatment with rituximab and bendamustine.

Conclusion：This case illustrates that chronic inflammation due to thyroid-associated ophthalmopathy may have induced MALT lymphoma. Biopsy played a key role in the diagnosis.