白谷 理恵¹, 坂東 裕子², 岡崎 舞¹, 澤 文¹, 井口 研子², 近藤 譲³, 原 尚人²

Rie SHIRATANI¹, Hiroko BANDO², Mai OKAZAKI¹, Aya SAWA¹, Akiko Iguchi-Manaka², Yuzuru KONDO³, Hisato HARA²

¹筑波大学附属病院乳腺甲状腺内分泌外科, ²筑波大学医学医療系乳腺内分泌外科, ³独立行政法人国立病院機構霞ヶ浦医療センター病理診断科

¹Department of Breast, Thyroid and Endocrine Surgery, University of Tsukuba Hospital, ²Department of Breast and Endocrine Surgery, Institute of Medicine, University of Tsukuba, ³Department of Pathology, Kasumigaura Medical Center

キーワード : Cowden syndrome, PTEN hamartoma tumor syndrome, breast cancer

Cowden症候群では，乳房に乳管過形成や乳頭腫，腺症や線維腺腫などの良性疾患に加え，悪性腫瘍も生じやすく，鑑別が難しい場合がある．症例は35歳女性．子宮内膜癌や甲状腺癌の既往がある．19年以上前より両側乳房に多発腫瘤を指摘されていた．右乳房に新規の腫瘤を自覚し精査を行った．乳房超音波では両側乳房に多発かつ多彩な乳腺腫瘤や乳腺症様の所見を認めた．患者が自覚した嚢胞内腫瘤に対する吸引式組織生検により非浸潤性乳管癌が疑われた．造影MRIでは対側にも悪性を疑う病変を指摘され，精査の結果，同時性両側乳癌の診断で両側乳房全切除術，両側センチネルリンパ節生検，両側腋窩リンパ節郭清術を施行後，放射線照射，抗癌剤治療が行われ，現在ホルモン治療を継続中である．マルチ遺伝子パネル検査ではPTEN遺伝子の生殖細胞系列病的バリアントを認めた．

In Cowden syndrome, benign breast conditions such as ductal hyperplasia, intraductal papillomatosis, adenosis, and fibroadenomas as well as cancers can occur, which may be difficult to distinguish. This case was a 35-year-old Japanese woman who had a history of thyroid follicular carcinoma and uterine cancer. She had multiple breast lesions and had been followed up with ultrasonography for about 19 years. She noticed a new lump in her right breast on her own, and ultrasonography showed a new intracystic tumor among various lesions, which was diagnosed as suspected cancer using vacuum-assisted breast biopsy (VAB). Contrast-enhanced magnetic resonance imaging showed a lesion on the contralateral side that was also suspected to be malignant. Bilateral mastectomy, bilateral sentinel lymph node biopsy, and bilateral axillary dissection were performed. She received adjuvant chemotherapy and radiation therapy, and she is taking anastrozole. Multi-gene panel testing showed germline pathological variants of the PTEN gene.