Objective: To describe the cytologic features of invasive micropapillary carcinoma of the breast, a distinct, unusual variant of infiltrating duct carcinoma characterized histologically by pseudopapillary structures lacking fibrovascular cores and tubuloalveolar structures floating freely within clear spaces separated by a delicate fibrocollagenous stroma and characterized clinically by prominent lymphotropism and an aggressive clinical course.
Study design: We reviewed the clinical, cytologic, histologic, immunohistochemical and flow cytometric features in 11 cases of invasive micropapillary carcinoma of the breast diagnosed preoperatively by fine needle aspiration.
Results: All patients were women, ranging in age from 31 to 83 years. A preoperative diagnosis of malignancy was made in all cases. Tumor size ranged from 1.2 to 5.5 cm. Ten patients had lymph node metastases. Cytology was characterized by a "dual" pattern formed by round or angulated, three-dimensional, cohesive clusters of neoplastic cells with pseudopapillary configuration and two-dimensional, dyscohesive aggregates and single cells with high grade nuclei and intact cytoplasm.