乳房低形成を合併したBecker母斑症候群にレーザー照射を行い症状の改善を認めた1例

A Case of Beckerʼs Nevus Syndrome Complicated by Breast Hypoplasia with Symptom Improvement After Laser Irradiation

はじめに

　Becker母斑は1949年にBeckerにより，青年の肩部に発生した後天性の多毛を有する淡褐色斑として初めて報告された 1）2）。また，Becker母斑症候群は，Happleら 3）により1997年に初めて提唱された疾患概念である。皮膚症状としてのBecker母斑に加え，母斑と同側の皮膚・骨・筋の欠損や形成異常を合併するまれな症候群である。

　Becker母斑は通常，前上部体幹の周囲によく発生する不規則な形の色素沈着斑からなり，多毛や痤瘡様病変を伴う。病理組織学的には，表皮基底層にわずかにメラニンが増生し，真皮浅層にメラノファージを認める。また，平滑筋線維の増加を特徴とする。

　本邦においてBecker母斑症候群は，渉猟し得た限り本症例を含め8例の報告しかなく，極めてまれな症候群と考えられる。今回われわれは思春期早発症患者に乳房低形成を合併したBecker母斑症候群の1例を経験したので，これまでの報告例とともに若干の考察を加えて報告する。

　We report the case of a 12-year-old female who presented to our hospital with complaints of breast asymmetry and hyperpigmented macules on the side. Based on these symptoms, Beckerʼs nevus syndrome was diagnosed. This syndrome is characterized by the presence of a Beckerʼs nevus along with ipsilateral breast hypoplasia or hypoplastic defects of the muscle, skin, or skeleton. The patientʼs Beckerʼs nevus syndrome is a rare and typically benign condition within the group of epidermal nevus syndromes, and it was treated with laser therapy to address hyperpigmentation in the patientʼs left breast, resulting in an improvement in the size of the hypoplastic breast. Several reports suggest that irradiated lasers reduce the sensitivity of remaining melanocytes to androgen receptors, potentially improving bone and soft tissue hypoplasia, along with the disappearance of brown spots.

　Spironolactone, an internally administered androgen antagonist, has shown efficacy against breast hypoplasia. Noninvasive androgen antagonist therapy should be initiated in similar cases, and if it is ineffective, a mammoplasty should be considered according to the patientʼs preference.

Clinicians should keep in mind the possible diagnosis of Beckerʼs nevus when they encounter pigmented lesions on the scapular or anterior thoracic region. If Beckerʼs nevus is suspected, the patient should be examined for breast hypoplasia and musculoskeletal abnormalities, and any complications should be treated in collaboration with other medical departments such as endocrinology, orthopedics, and dermatology.