FISH is the method of choice for assessment of Her-2/neu gene status, especially if equivocal cases are not accompanied by true gene amplification in cases of breast carcinoma.
HER 2 IMMUNOHISTOCHEMISTRY ASSAYS
Score: 0
Her 2 Status: Negative
Staining pattern: No staining or membraine staining in <10% of tumour cells
Score: 1+
Her 2 Status: Negative
Staining pattern: A barely perceptible membrane staining is detected in >10% of tumor cells. The cells are stained only in part of membrane
Score: 2+
Her 2 Status: Equivocal
Staining pattern: Weak to moderate complete membrane staining is seen in >10% of tumor cells or <30% with strong staining
Score: 3+
Her 2 Status: Positive
Staining pattern: Strong complete membrane staining is seen in >30% if tumor cells