Limitations of Immunohistochemistry in Metastatic Cancer
The immunohistochemical diagnosis of malignant mesothelioma therefore depends on the use of a panel of stains that includes markers that are commonly expected to be positive and negative in these tumors. Immunohistochemistry (IHC) remains a cornerstone of tumor classification. Panels of antibodies detect protein markers associated with tissue lineage. However, IHC has limitations: marker overlap between tumor types.
Immunohistochemistry has become an essential ancillary examination for the identification and classification of carcinomas of unknown primary site (CUPs). Reduced expression in poorly differentiated tumors, limited tissue sample availability, and subjective interpretation variability are key challenges. In diagnostically ambiguous cases, molecular profiling offers an objective, quantitative complement to protein-based assays.
IHC is a useful method to identify primary tumor sites in patients with node metastasis. In our series, IHC was needed in 11.69% of the cases. The limitations extend to cases where tumors lose antigenicity or exhibit aberrant expressions, complicating accurate classification in metastatic settings.
