We report a case of a patient with invasive breast carcinoma that demonstrated HER-2 gene amplification on core biopsy, who relapsed while on adjuvant trastuzumab therapy after her mastectomy and ultimately died 15 months after diagnosis. Surprisingly, analysis of multiple metastases harvested at rapid autopsy demonstrated no evidence of HER-2 gene amplification. Retrospective examination of the carcinoma in the patient's mastectomy specimen revealed only focal HER-2 amplification within the tumor,...