Metaplastic Variant of Invasive Micropapillary Breast Carcinoma

Abstract

Invasive micropapillary carcinomas (IMC) and metaplastic breast carcinoma (MBC) have different clinicopathologic features. This study reports an unusual case of multifocal grade III IMC associated with MBC component in a 35-year-old woman. MBC was vimentin positive, pancytokeratin negative, and showed focal p63 positivity. Immunostains for estrogen and progesterone receptor, and fluorescence in situ hybridization for Her2/neu amplification were negative. All the left axillary lymph nodes dissected were positive for metastatic carcinoma with ductal and IMC patterns, but without metaplastic component. Postmastectomy computed tomography and magnetic resonance imaging scans showed metastases to lungs, liver, brain, and vertebrae. The biologic behavior of tumor was in accordance with histology, so that the nodal and distant metastases were testament to the underlying inherently aggressive IMC, whereas large tumor size and triple negativity reflected the features of MBC. To the best of the authors' knowledge, this is the first report of a metaplastic variant of invasive micropapillary breast carcinoma with triple negative phenotype.

Metaplastic carcinoma of the breast with squamous differentiation: prognostic factors and multidisciplinary treatment

“…Like other metaplastic carcinomas, these tumors do not express hormonal receptors or Her 2, and have an unfavorable prognosis as compared with other triple-negative tumors, possibly due to their poor response to usual chemotherapeutic treatment [ 20 , 21 ]. In an immunohistochemical study, marker p63 may be recognized in the squamous element, which facilitates classification; and they present positive cytokeratin [ 22 , 23 ].…”