色素分界線の知見補遺

DEMARCATION LINES OF PIGMENTATION

I．緒言

　1913年松本^1）2）は腋窩上界において上腕内面より胸部にかけ，また大腿内側においては会陰部より膝窩内縁にわたり，ほぼ線状をなす色素分布の境界線を認め，これを「Voigt境界線において，しばしば見られる皮膚色素分布の境界」と題して報告されて以来，色素分界線は本邦において三浦（修）^3）−5），原田ら^6），松本^7），伊藤^8）等の報告に接するが，本症は余り目立たないこと，自覚症状のないこと，また後記するごとく，進行性に漸次著明となる例はほとんど認められなかつたことなどより，これを主訴として来院する患者は非常に少ない。このようなことから本症の報告は少なく解明されていない点も多々あるものと思われる。これまでの本症の報告は本邦人のみで，白人や黒人ではむしろ色の濃淡の差がはつきりせず，判定しにくいような理由もあつて未だ外国人にみられたという報告はない。

　本症の分布より色素形成と神経との関連性が推測されるため，これの研究は皮膚色素異常症の解明に役立つものと考え，私どもはこれまでに皮膚科診察の際などに本症の存在を注意深く観察すると共に，学校検診においてその頻度等を調査し，得られた症例について組織検査を含めて種々の検索を加えたので，ここに報告する。

Demarcation lines of pigmentation are defined to be a peculiar boundary line between hypomelanotic and hypermelanotic areas of the skin, usually distributed along the ventral axial line of the limbs, and seldom along the both parasternal lines. No report of these lines has been found in any other races than Japanese people.

1. Out of 42 subjects with demarcation lines of pigmentation examined, the lesions were found on the upper arms and/or chest in 29, on the lower extremities in 11, and on the parasternal regions in the remainder.

2. The lesions are usually symmetrical. In two cases of the 42, however, the lesions were found only on the left arm.

3. In the lesions, distributed on the ventral axial line of arm, the tinge of skin color was uniform, and formed a sharply demarcated line of pigmentation, but in ones on the lower extremities, abundant follicular pigmented spots of less than 2 mm were found on the hypermelanotic areas.

4. Demarcation lines of pigmentation are supposed to occur insidiously before adolescene, but might be present at birth or appear soon after birth.

5. Difference of pigmentation between the adjacent areas in the demarcation lines of pigmentation was found to be based on larger amount of melanin granules in the basal layer of hyperpigmented areas than in that of hypopigmented.

6. Demarcation lines of arms and chest were observed in about 4 per cent on a group examination of upper body in 561 teenagers. There seemed to be sexual predilection.