ERBB2 and breast carcinoma: The discordant cases consisted of 3 breast carcinomas with low cellularity and an infiltrative pattern of growth (cases #66, #67, and #76) and a lymph node metastasis from breast carcinoma (cases #78), all visually classified as HER2-positive (ISH group 1) and classified by IA as HER2-negative (ISH groups 5, 2, 5 and 4, respectively), with an average of HER2 copy number per cell higher than 3.0 (Table 3, Figs. 2 and 3).