Diagnostic Utility of SATB2 in Metastatic Krukenberg Tumors of the Ovary: An Immunohistochemical Study of 70 Cases With Comparison to CDX2, CK7, CK20, Chromogranin, and Synaptophysin.

SATB2 is a sensitive marker for colorectal adenocarcinomas. No study has investigated its diagnostic utility in metastatic Krukenberg tumors (MKTs) of the ovary. Here we performed immunohistochemical staining SATB2 in 70 MKTs of various origins (stomach 27, colorectum 13, appendix 20 including 19 metastatic adenocarcinomas ex goblet cell carcinoids [AdexGCC] and 1 conventional poorly differentiated carcinoma with signet ring cells, breast 5, bladder 3, lung 2) to assess its diagnostic utility. We also compared SATB2 with CDX2, CK7, CK20, chromogranin, and synaptophysin in MKTs of gastric origin (MKTs-stomach), those of colorectal origin (MKTs-colorectum) and those due to appendiceal AdexGCCs (MKT-AdexGCCs) for their sensitivity and specificity to distinguish these tumors. SATB2 staining was seen in 1/27 (4%) MKTs-stomach (40% cells), 7/13 (54%) MKTs-colorectum (mean: 17% cells, median: 7%, range: 2% to 60%), and 19/19 (100%) of MKT-AdexGCCs (mean: 97% cells, median: 100%, range: 80% to 100%) (P<0.01 between any two). SATB2 staining was seen in 1/1 metastatic appendiceal poorly differentiated carcinoma with signet ring cells (5% cells), 1/3 MKTs of bladder origin (60% cells), 0/2 MKTs of pulmonary origin, and 1/5 MKTs of breast origin (10% cells). SATB2 staining was diffuse strong in MKT-AdexGCCs whereas in other MKTs it was focal and weak in the signet ring and nonsignet ring nonglandular cells and from focal weak to diffuse strong in well-formed glands. MKTs-stomach, MKTs-colorectum, and MKT-AdexGCCs showed no significant staining difference in CDX2 (100%, 100%, 100% cases, respectively; P=1.0), CK20 (96%, 100%, 100%, respectively; P=1.0), chromogranin (59%, 31%, 63%, respectively; P>0.05) or synaptophysin (59%, 63%, 84%, respectively; P>0.05) but they had significant difference in CK7 staining (93%, 8%, 42%, respectively; P<0.05). Among these 6 markers, SATB2 is the best one to distinguish MKT-AdexGCCs from MKTs-stomach (100% sensitivity, 96% specificity) and MKTs-colorectum (100% sensitivity and 100% specificity if staining more than 75% tumor cells as the cutoff). In distinguishing MKTs-stomach from MKTs-colorectum, SATB2 is not as good as CK7 which is the best marker. Our results indicate that SATB2 is a highly sensitive marker (100% sensitivity) for metastatic MKT-AdexGCCs with high specificity (100% specificity when showing strong staining in at least 75% cells) among MKTs. SATB2 is a useful marker for determining the primary sites of MKTs of the ovary.