Diagnosis of metastatic neoplasms: An immunohistochemical approach

Context:-It is important to determine the type and/or site of origin of metastatic tumors for optimal clinical management. Objective:-To summarize the use of currently available immunohistochemical markers in the evaluation of metastatic tumors. Data Sources:-Review of relevant literature on immunohistochemical evaluation of tumors and the author's personal experience. Conclusions:-Immunohistochemistry is an important ancillary technique for evaluation of metastatic tumors and should be used in the context of routine morphology and clinical information. While a single marker may be used to support a known or suspected site of origin, a carefully constructed panel is strongly recommended, particularly for tumors of morphologically uncertain lineage or origin.