Low‐grade adenosquamous carcinoma of the breast: A case report with cytologic findings and review of the literature

The cytological and histopathological featurn of a case of low‐grade adenosquamous carcinoma of the breast In a 47‐year‐old Japanese female was studied. The fine needle aspl rstlon blopsy specimen of this case revealed prolfferating ductal cells and atyplcal squamous cells In the same cell clusters. The resected left breast mass had a relatively well‐circumscribed hard mass measuring 1.6 cm at its greatest dimension. Histologic examination demonstrated the coexistence of atypicai squamous and ductal components in the same lesion, with transition between these two components. Desmoplastic stomal reaction was observed. The majority of ductal components had a two‐layered composition, and sclerosimg adenosls‐like lesions were also observed at the periphery of the tumor. Based on these cytoiogic and histological findings, this tumor was diagnosed as low‐grade adenosquamous carcinoma of the breast This is the first report of the cytological findings of low‐grade adenquamous carcinoma of the breast, and It is Important for pathologists to consider the possibility of low‐grade adenosquamous carcinoma when the cytologlcal findings described above are present in an aspiration cytology specimen of the breast.