Two cases of occult breast cancer presenting as metastatic axillary tumor

症例1は72歳女性.右腋窩リンパ節腫脹を主訴に当科受診した.乳癌の腋窩リンパ節転移を疑いマンモグラフィ(MMG),超音波検査(US),CT,MRIで検索を行ったが原発不明であった.腋窩リンパ節生検の結果,浸潤性小葉癌であった.潜在性乳癌の診断で乳房切除,腋窩リンパ節郭清を施行した.症例2は60歳女性.右腋窩リンパ節腫脹を主訴に当科受診した.症例1と同様に各検査で原発不明であった.腋窩リンパ節生検の結果,浸潤性乳管癌であった.潜在性乳癌の診断で乳房切除,腋窩リンパ節郭清を行った.症例1,2ともに術後3年間無再発で経過している.全乳癌における潜在性乳癌の頻度は0.3-1%^{1,2)}と稀であり,各施設が個別に治療方針を決定している.不十分な治療は再発転移の可能性を高めるが,過剰な治療も控えるべきであるため治療方針の決定には苦慮する.体系化された治療指針を作成するためには症例の蓄積が必要と考える.

ACase 1:A 72-year-old woman visited us with a complaint of right axillary lymph node swelling. Breast cancer metastases to the axillary lymph nodes were suspected. Even with mammography(MMG),ultrasound(US),computed tomography(CT),and magnetic resonance imaging(MRI),the primary lesion could not be identified. Axillary lymph node biopsy revealed invasive lobular breast carcinoma. She was diagnosed with latent breast cancer and underwent mastectomy and axillary lymphadenectomy. Case 2:A 60-year-old woman visited us with a complaint of right axillary lymph node swelling. Despite various examinations, including MMG, US, CT and MRI as in Case 1, the primary lesion could not be identified. Axillary lymph node biopsy revealed invasive ductal breast carcinoma, leading to a diagnosis of latent breast cancer. She underwent mastectomy and axillary lymphadenectomy. Postoperatively, both patients have remained recurrence-free for two years to date. Latent breast cancer develops at a low incidence, 0.3-1% of all breast cancers, and therapeutic strategies are determined on an individual basis at each institution. While insufficient treatment increases the possibility of recurrence and metastasis, excessive therapy should be avoided. Therefore, determining the optimal therapeutic strategy can be challenging. We advocate accumulating more cases to establish systematic therapeutic guidelines.

潜在性乳癌