Different expression of HER2/neu oncogene in breast carcinoma and in liver metastasis. Description of a case.

We report the clinical, morphological and molecular findings
regarding a 37-year-old woman with breast cancer metastatic
to the liver and describe the different expression of a tumor
marker in the primary and secondary lesions and the singular
responsiveness to treatment. The patient suffered from a carcinoma
of the left breast with metastasis to the liver. High
HER-2 protein expression assessed by immunohistochemistry
and HER-2/neu amplification determined by FISH were present
in the primary tumor, while the liver metastasis showed a lower
value of HER-2 protein (2+) and absence of HER-2/neu amplification.
The patient was treated with chemotherapy (epirubicin
and paclitaxel) followed by trastuzumab and docetaxel.
After 5 months, at the completion of chemo-immunotherapy,
liver ultrasonography showed a further hepatic response. A
second biopsy was performed on the residual liver nodule: immunohistochemistry
revealed negative (1+) HER-2 expression
and FISH confirmed that the HER-2/neu gene was not amplified.
The different amplification of HER-2 and expression of its
protein in primary and metastatic carcinoma could be important
for planning adequate treatment.