Solid papillary carcinoma of the breast: imprint cytological and histological findings.

Solid papillary carcinoma is a rare breast lesion, but this entity remains poorly recognized. In this article, we report a case of solid papillary carcinoma of the breast with focus on cytological and histological findings. A 66-year-old Japanese woman presented with nipple discharge. Imprint cytology obtained from the surgically resected breast specimens showed a plasmacytoid appearance and spindle cell morphology with low-grade atypia. Histologically, the tumor revealed findings of solid papillary carcinoma and predominantly showed an intraductal lesion with focal minimal invasion into the breast parenchyma. Fibrovascular cores with hyalinization were seen. Proliferation of short spindle cells was also focally observed. Pseudorosette formation or nuclear palisading at the stromal-glandular interface was seen, and intracellular or extracellular mucin deposition was occasionally identified. Nuclear atypia generally showed low grade. Finally, clinicians, cytotechnologists, and pathologists should recognize this rare tumor entity because this tumor is a malignant neoplasm showing characteristic pathological findings.