Abstract
The differential diagnosis of metastases with no known history or a poorly differentiated subtype may present a diagnostic challenge – especially for small biopsy specimens. This study evaluated rabbit monoclonal anti-SATB2 by immunohistochemistry for neoplastic expression, sensitivity, and specificity. Ninety-five percent of primary colorectal adenocarcinoma cases displayed strong and diffuse nuclear staining with rabbit monoclonal anti-SATB2. Anti-SATB2 showed diffuse, weak, and nuclear expression in a case of medullary carcinoma of the colon, while other common colorectal markers showed no immunoreactivity. Anti-SATB2 also showed strong and diffuse nuclear staining in colorectal adenocarcinoma metastases to uterus, liver, lymph nodes, and lung (11/11, 100%). SATB2 rabbit monoclonal antibody is a sensitive and specific marker for malignancies of lower GI origin and is useful for differential diagnosis of metastatic adenocarcinomas of unknown primary.