Table 2.
Useful immunohistochemical antibodies in the differential diagnosis of urachal adenocarcinoma (UrC), colorectal adenocarcinoma (CRC), and primary bladder adenocarcinoma (PBAC). Loss of MMR proteins (MLH1, MSH2, MSH6, and PMS2) additionally favors colorectal over urachal adenocarcinomas. For more details on reactivity rates, number of cases, and references, please refer to Supplementary Table 2. Please note that data density is low for most antibodies limiting significance. “Highest” data quality is available for CK7, β-Catenin, and CEA.−: negative (0% positive); (−): mostly negative (1–25% positive); +/−: some positive (26–50% positive); (+): mostly positive (51–75% positive); +: positive (76–100% positive).
| Reactivity | Differential diagnosis | |||||
|---|---|---|---|---|---|---|
| Biomarker (IHC) | UrC | CRC | PBAC | UrC versus CRC and PBAC | UrC and PBAC versus CRC | UrC and CRC versus PBAC |
| AMACR (p504s) | (−) | + | (+) | + | − | − |
| CK34βE12 (HMWCK) | (+) | (−) | +/− | + | − | − |
| CK7 | (+) | +/− | (+) | − | + | − |
| β-Catenin (nuclear) | (−) | + | (−) | − | + | − |
| CD15 (Leu-M1) | + | +/− | (+) | − | + | − |
| CEA | + | + | (+) | − | − | + |
| GATA3 | − | − | (+) | − | − | + |