Abstract

Micro-papillary carcinoma breast emerges as an invasive, exfoliative neoplasm delineating characteristic pseudo-papillary, tubular or morula-like epithelial structures with an inverted or ‘inside out’ tumour pattern. Tumefaction exhibits upregulation of various nutrient transporters as glucose transporter 1 (GLUT1) through activation of transcription factor as hypoxia-inducible factor or upregulation of BC-1514 (C21 or f118), especially within micro-papillary areas. Tumour cells exhibit gains of chromosome 1q, 8q, 17q, 20q and loss of chromosome 1p, 8p, 13q, 16q and 20q. Cellular cytological smears delineate angulated clusters, abortive papillae and isolated malignant cells. Densely cellular tufts of cells configure pseudo-papillae, hollow tubules or morula with circumscribing clear spaces and minimal encompassing fibro-collagenous stroma. Characteristic reverse polarity or an ‘inside out’ pattern of tumour cells pervaded with abundant, eosinophilic cytoplasm, intracytoplasmic mucin and nuclei with a peripheral bulge, knobby or serrated appearance is observed. Neoplastic cells appear immune reactive to Epithelial Membrane Antigen (EMA), CD15s, E-cadherin, p120 catenin, oestrogen receptor(ER), Progesterone Receptor (PR), HER2 or GATA3.

Keywords:Pseudo-papillae; Reverse polarity; Anti-oestrogen therapy