Albinoidismにみられる雀卵斑について

EPHELIDES IN ALBINOIDISM

I．緒言

　雀卵斑は普通，肌色の異なつた各個体にみられるが，一般に赤毛，青い眼の人に雀卵斑の程度が強く，色素斑も大きく，しかもこれらの人達の皮膚は紫外線照射に対して感受性が強いことが知られている。一方，髪の毛の黒化度の強い程，雀卵斑の数は少なく，形も小さく，紫外線に対する皮膚の感受性も減少しており，これらの人の眼は一層黒い人が多い^1）。日本人でも皮膚色の白い人に多くみられる傾向にあるが，しばしば家族発生も認められ，遺伝的関係のあることが知られている^2）3）。

　albinismは全身の皮膚，毛髪および眼のメラニン色素の欠如によつて特徴づけられる。その中に，年齢の進むにつれて皮膚，毛髪および眼に少量のメラニン形成がみられるようになり，また紫外線照射によつて皮膚に軽度の点状色素斑が出現して来るincomplete albinismが含まれている^4）。それとは別に皮膚や毛髪のメラニン欠如は不完全であり，眼球震盪や羞明などの眼症状はみれらないか軽度に認められ，また年齢の進むにつれてメラニン形成がかなり行なわれるようになるalbinoidismは，紫外線照射を頻回にうけると，露出部などでは皮膚は褐色調を示すようになり，また雀卵斑を来たす場合も多い^5）〜7）。普通にみられる雀卵斑は顔面，特に鼻背より両頬部に主として対称的に集簇して出現するのに対し，albinoi-dismにみられる雀卵斑は露出部に出現するものの，特に顔面に限局するというのでなく，また一般に数も少なく，まばらで，間もなく消褪する場合が多く^7），幾分臨床像も普通の場合と異なつている。

A case of albinoidism is reported in a 7-year-old Japanese boy, which has been accompaniedby generalized ephelides since 18 months of age. The sunburn frequently appeared on the irra-diated areas by sunlight, and he has also complained of a slight photophobia. The skin color of the patient is as white as that of Caucasian. Extensive brownish pigmented spots of 2 to 5mm. in diameter are seen over the whole body surface, and the skin color of the exposed areas is slightly reddish brown. Histologic findings disclosed just little amount of melanin granules at the basal layer of the surrounding area of ephelides, that is, albinoid skin. The lesion of ephe-lides showed hyperpigmentation of the basal layer with little or no elongation of the rete ridges. Over a period of three years' observation, the lesions of ephelides were confirmed to increase in number in summer, especially following irradiation of the skin with the ultraviolet light, but to decrease and become faint in winter. These pigmented spots not always appear the same sites as before.

In albinoidism, hypomelanosis was found over the entire body, and the contents of the epider-mal melanin are also significantly less than those in normally pigmented Japanese. It would be reasonable to consider, thus, that both inflammatory changes and the pigmented spots following irradiation of the ultraviolet light more easily occur in the former, because of intolerance of ultraviolet radiation. Alternately, there would be a possibility that the gene or genes of albi-noidism and that of ephelides are linked or simultaneously loaded in the same individual.