To further evaluate CD56 expression in breast cancer we collected a small cohort (n = 33) of breast cancer cases with whole tumor tissue embedded in paraffin blocks and clinical follow-up data (n = 33; Luminal A [n = 11], Luminal B [n = 3], HER2 [n = 6], TNBC [n = 13]). The gene discussed is ERBB2; the disease is breast carcinoma.