AMACR and metastatic neoplasm: We also included other markers mostly used in the differentiation of non-serous ovarian and metastatic tumors, such as MUC4, CDX2, SATB2, HNF1B, napsin A, TTF1, AMACR, and ARID1A which have not yet been thoroughly investigated on a large sample set of serous tumors, and we found positive expression of these markers in only a small number of cases.