球結膜の原発性後天性メラノーシスの若年者例

A juvenile case of primary acquired melanosis of the bulbar conjunctiva

　16歳頃に自覚した球結膜色素沈着巣が増強拡大してきた21歳女性に対して，切除生検を行い，異型性を示す原発性後天性メラノーシスと診断された症例を経験した。初回切除後，癒着の強かった角膜輪部の色素と残存組織から色素散布を認め，約4か月後には色素沈着の再発をみた。第2回目広範囲完全切除生検の結果，初回に比べて異型の程度は弱かったが，約2か月後に小さな色素再発を認めた。今後さらに拡大する可能性と頻回切除による悪性化の誘発を考え，冷凍凝固術を施行した。以後，新たな色素再発は認めていない。若年者の球結膜色素斑のなかでも稀に悪性黒色腫へ進行する例があることを考慮し，早期診断と完全切除が必要である。

A 21-year-old female presented with brownish pigmentation in the bulbar conjunctiva in her right eye. The lesion became manifest and enlarged since 5 years before. Biopsy of excised specimen showed diffuse hyperpigmentation in the basal layer and atypical melanocytes in the conjunctiva. She was diagnosed as primary acquired melanosis (PAM) with atypia. Conjunctival and corneal epithelialpigmentation reappeared in the residual tissue 4 months after surgery. A second excision was perfor-med including the corneal epithelium. Specimen from the conjunctiva showed PAM with moderate atypia. Specimen from the cornea showed hyper-pigmentation without atypical melanocytes.Despite extensive excision, minor pigmentation along the limbal conjunctiva recurred 2 months later. Cryotherapy using double freeze-thaw tech-nique proved successful.