Figure 1.

EGFR overexpression and gene amplification in MBCs. Photomicrographs of (a) a spindle cell metaplastic breast carcinoma (haematoxylin and eosin) showing (b) grade 3+ immunohistochemical positivity for EGFR and (c) EGFR gene amplification (>5 signals per nucleus [CISH]). Inset in panel c: note the bizarre neoplastic cell with more than 10 copies of EGFR. (d) Breast carcinoma with squamous metaplasia (haematoxylin and eosin) with (e) EGFR grade 3+ immunohistochemical positivity. (f) CISH demonstrating EGFR amplification (clusters of signals in the nuclei of neoplastic cells). Note the presence of one or two signals in the nuclei of stromal cells (arrowheads). CISH, chromogenic in situ hybridization; EGFR, epidermal growth factor receptor; MBC, metaplastic breast carcinoma.