ESR1 and eccrine carcinoma: To investigate whether apocrine-eccrine carcinomas express hormonal receptors or possess activation of oncogenic pathways that could be targeted by available chemotherapeutic agent we performed immunohistochemistry for AR, ER, PR, EGFR, and HER2 expression; fluorescence in situ hybridization (FISH) for EGFR and ERBB2 gene amplification; and single base extension genotyping [24] for recurrent mutations in 15 cancer genes including AKT-1, EGFR, PIK3CA, and TP53 on an expanded series of 54 cases of apocrine-eccrine carcinomas (Table 1).