Objective: In the current work, we compared HER2 by fluorescence in situ hybridization and estrogen and progesterone receptors by immunohistochemistry in matched primary breast carcinomas and their lymph node metastases.
Material and Method: Thirty-nine cases of primary and lymph node metastases were assessed for HER2. Primary tumors of the cases selected were known to be HER2 negative. Also, immunohistochemistry for estrogen and progesterone receptors was performed on 36 cases from the same cohort to assess any discrepancy between the primary tumor and the lymph node metastases.
Results: Out of 39 cases, one case was HER2 amplified in lymph node metastasis compared to non-amplified primary tumor. Approximately eight percent of cases (3/36) were estrogen receptor-negative in LN metastasis and 5.55% (2/36) were less strongly positive compared to the positive primary tumors. Nineteen percent (7/36) were progesterone receptor-negative in lymph node metastasis in contrast to the matched positive primary tumors, and 5.55% (2/36) were progesterone receptor-positive in lymph node as compared to their corresponding negative primary tumors.
Conclusion: While most matched primary breast tumors and lymph node metastases show concordance in HER2, estrogen and progesterone receptor status, we confirmed the multiple reports that identified discordant results in a subset of cases. These results support the newly adopted guidelines that require testing for HER2 on metastatic lesions.