中村 桂子¹, 高島 勉², 日野 雅之³, 藤岡 一也¹, 武田 節子¹, 荻澤 佳奈⁴, 川尻 成美², 小野田 尚佳², 石川 哲郎², 平川 弘聖²

Keiko NAKAMURA¹, Tsutomu TAKASHIMA², Masayuki HINO³, Kazuya FUJIOKA¹, Setsuko TAKEDA¹, Kana OGISAWA⁴, Hidemi KAWAJIRI², Naoyoshi ONODA², Tetsuro ISHIKAWA², Kosei HIRAKAWA²

¹大阪市立大学医学部附属病院中央臨床検査部, ²大阪市立大学大学院腫瘍外科, ³大阪市立大学大学院血液内科, ⁴育和会記念病院外科

¹Central Clinical Laboratory, Osaka City University Hospital, ²Department of Surgical Oncology, Osaka City University Graduate School of Medicine, ³Department of Hematology, Osaka City University Graduate School of Medicine, ⁴Department of Surgery, Ikuwakai Memorial Hospital

キーワード : ultrasonography, extramedullary relapse, breast, leukemia

急性骨髄性白血病（AML）の乳腺への髄外浸潤はまれである．今回我々は，AMLが乳腺に髄外再発した2症例を経験したので報告する．症例1は32歳女性．25歳時AMLと診断され化学療法により一旦寛解を得たが，再発を来たし同種骨髄移植を受け，再び寛解となった．31歳時，鼻腔に軟部腫瘤性病変が出現し生検によりAMLの髄外再発と診断された．同時期に左乳房腫瘤も指摘され，超音波検査にて乳房内下区に分葉状の低エコー腫瘤像を認めた．針生検にて白血病細胞の浸潤を認めた．化学療法後，乳房腫瘤は縮小し切除を行った．病理診断は白血病細胞の浸潤であった．また，骨髄検査では完全寛解であった．症例2は20歳男性．AMLと診断されたが，初診時より視触診にて女性化乳房を認めた．3回の寛解導入療法を施行したが寛解には至らず，同種骨髄移植を受けて寛解となった．その時点で女性化乳房は消失していた．AMLの寛解から半年後より徐々に増大する両側乳頭下の硬結を認め，超音波検査にて境界は比較的明瞭平滑であるが内部は低エコーで不均質な腫瘤像を認めた．カラードプラ法では内部に分岐した血流シグナルを認め，針生検を行った結果，白血病細胞の浸潤を認めた．また，同時期に施行された骨髄検査でも白血病細胞を認め，白血病の再発と診断された．造血器悪性腫瘍が背景にある患者に乳腺腫瘤を認めた場合には，髄外再発も念頭において検査を行う必要があると思われる．

We encountered two rare cases of extramedullary relapse of acute myeloid leukemia (AML) in mammary gland. [Case 1] A 32-year-old woman who had received intensive chemotherapy for AML achieved complete remission. The AML relapsed 3 years later, at which time allogenic bone marrow transplantation was performed. Six years after initial presentation, a soft tissue mass appeared in the nasal cavity. Biopsy revealed extramedullary relapse of the AML. At the same time, a breast tumor was detected. Ultrasonography showed a lobular-shaped and hypoechogenic tumor in the lower medial quadrant of the left breast. Core needle biopsy showed infiltration of leukemia cells. Although bone marrow biopsy showed no leukemia cells after chemotherapy for AML, the breast tumor remained. A lumpectomy of the breast tumor was performed. The pathological diagnosis of the surgical specimen was invasion of myeloid leukemia in the breast. [Case 2] A 20-year-old man was diagnosed with AML and bilateral gynecomastia. After the patient failed to respond to induction chemotherapy three times, allogeneic bone marrow transplantation was performed, which successfully induced complete remission. The bilateral gynecomastia subsided after remission. Six months after remission, bilateral breast lumps gradually increased in size. Ultrasonography showed hypoechogenic breast tumors with smooth borders under the nipples. Branched blood flow signals were detected in the tumors by color Doppler mode examination. The ultrasonographic findings suggested malignant disorder. Core needle biopsy showed infiltration of leukemia cells in the bilateral breasts. Bone marrow biopsy also showed leukemia cells, prompting a diagnosis of relapsed AML. Extramedullary relapse must be considered when a patient with hematopoietic malignancy develops a breast tumor.