Immunochemistry

Immunohistochemical studies play an important role for the pathologist in differentiating malignant mesothelioma from neoplastic mimics, such as breast or lung cancer that has metastasized to the pleura. There are numerous tests and panels available, but no single test is perfect for distinguishing mesothelioma from carcinoma or even benign versus malignant. The positive markers indicate that mesothelioma is present; if other markers are positive it may indicate another type of cancer, such as breast or lung adenocarcinoma. Calretinin is a particularly important marker in distinguishing mesothelioma from metastatic breast or lung cancer.