Broad-spectrum immunohistochemical epithelial markers: a review

A relatively large number of broad-spectrum immunohistochemical epithelial markers that can be used as part of the screening panels employed in the recognition of the main cell lineages during the initial evaluation of a poorly differentiated tumor are currently available. Variations exist in the sensitivity and specificity of the individual markers that have traditionally been used for the demonstration of epithelial differentiation and in the pitfalls associated with these markers. This article reviews not only the reactivity of the various pan-keratin antibodies that are often used to assist in the demonstration of epithelial differentiation, but also that of those that have recently become available. A review of the non-keratin, broad-spectrum epithelial markers that have been recognized as being useful is also presented.