各論① 木村病の診断と治療

Diagnosis and Treatment of Kimura’s Disease

はじめに

　木村病（木村氏病）は軟部好酸球肉芽腫とも呼ばれ，皮下軟部組織のリンパ濾胞の増殖を伴う慢性炎症性疾患である。無痛性腫瘤として全身の軟部組織に発生し得る。好発部位は顔面特に耳下腺部であり，頬部皮下腫瘍を主訴として形成外科を受診することもある。本症はアジア地域の若年男性に好発する良性疾患であり，血液検査所見では末梢血好酸球数とIgE値が上昇する。さらに組織中にもIgEの沈着と好酸球浸潤が認められるため，Ⅰ型アレルギーが関与していると考えられているがいまだ不明な点も多い 1）。本稿では，頬部に生じる皮下腫瘍の1つとして，本症の特徴と診断および治療法について述べる。

　Kimura’s disease, a benign disease that predominantly affects young males in Asia, is a chronic inflammatory disease with proliferations of lymph follicles in the subcutaneous soft tissues. Painless masses can occur in soft tissues throughout the body, but the parotid gland region of the face is the most common site of occurrence. Although Kimura’s disease is relatively rare, it is easy to diagnose based on its characteristics and blood test findings. There is no established treatment for this disease. Oral steroids are often the first choice, but the disease often relapses when the steroid dosage is reduced or discontinued. Steroids, cyclosporine, surgical therapy, and irradiation are commonly used in combination for Kimura’s disease. Surgical treatment is generally indicated when the mass is localized and small, but in some cases, surgery to reduce the mass may be performed for patients who would have difficulty undergoing a total resection. Mass reduction surgery can increase the efficacy of drug therapy and should be considered as an option. Individuals with Kimura’s disease and the chief complaint of a subcutaneous tumor in the buccal region may visit a plastic surgeon for surgical purposes. Although dermatologists and otolaryngologists often play a central role in first-line drug therapy, plastic surgeons should be actively involved in the surgical treatment of refractory cases.