Evaluation of Diagnostic Accuracy of Immunohistochemical Markers of SATB2 and Villin in Differential Diagnosis of Ovarian and Gastrointestinal Mucinous Carcinoma.

Determining the origin of mucinous adenocarcinomas can be challenging due to overlapping histologic and immunohistochemical features. This study evaluates the utility of SATB2 and villin immunohistochemical markers for defining mucinous adenocarcinomas' origin. We retrospectively analyzed 71 patients with mucinous adenocarcinomas-31 lower gastrointestinal (GI), 28 ovarian, and 12 cases of pseudomyxoma peritonei. Immunohistochemistry for SATB2 and villin was performed on ovarian and GI tumor samples. Sensitivity, specificity, and positive and negative predictive values were calculated to assess diagnostic performance.For identifying GI origin, SATB2 showed 87.1% sensitivity and 100% specificity, while villin exhibited 93.5% sensitivity but only 21.4% specificity. Dual SATB2/villin positivity demonstrated 80.6% sensitivity and 100% specificity for GI origin. For ovarian origin, dual SATB2/villin negativity provided 100% specificity. Logistic regression analysis on the adenocarcinoma cases showed 93.2% accuracy rate of dual staining with SATB2 and villin for predicting GI versus ovarian origin. SATB2 exhibits high specificity for GI mucinous adenocarcinomas, and villin is highly sensitive. Combining SATB2 and villin optimizes diagnostic performance for differentiating the primary origin site of mucinous adenocarcinomas and determining pseudomyxoma peritonei origin. Moreover, the presence of signet ring morphology prompted reconsideration of possible GI origin among our cases. A multimarker immunohistochemical panel, including SATB2 and villin can enhance the diagnostic accuracy of challenging mucinous adenocarcinoma cases.