tailieunhanh - Chapter 095. Carcinoma of Unknown Primary (Part 4)

There are 20 subtypes of cytokeratin (CK) intermediate filaments with different molecular weights and differential expression in various cell types and cancers. Monoclonal antibodies to specific CK subtypes have been used to help classify tumors according to their site of origin; commonly used CK stains in CUP are CK7 and CK20. CK7 is found in tumors of the lung, ovary, endometrium, and breast and not in those of the lower gastrointestinal tract, whereas CK20 is normally expressed in the gastrointestinal epithelium, urothelium, and Merkel's cells. CK20+/CK7– strongly suggest a primary tumor of the colon; 75–95% of colon tumors show. | Chapter 095. Carcinoma of Unknown Primary Part 4 There are 20 subtypes of cytokeratin CK intermediate filaments with different molecular weights and differential expression in various cell types and cancers. Monoclonal antibodies to specific CK subtypes have been used to help classify tumors according to their site of origin commonly used CK stains in CUP are CK7 and CK20. CK7 is found in tumors of the lung ovary endometrium and breast and not in those of the lower gastrointestinal tract whereas CK20 is normally expressed in the gastrointestinal epithelium urothelium and Merkel s cells. CK20 CK7- strongly suggest a primary tumor of the colon 75-95 of colon tumors show this pattern of staining. CK20- CK7 suggests cancer of the lung breast ovary endometrium and pancreaticobiliary tract some of these can also be CK20 . The nuclear CDX-2 transcription factor which is the product of a homeobox gene necessary for intestinal organogenesis is often used to aid in the diagnosis of gastrointestinal adenocarcinomas. Thyroid transcription factor 1 TTF-1 is a 38-kDa homeodomain-containing nuclear protein that plays a role in transcriptional activation during embryogenesis in the thyroid diencephalon and respiratory epithelium. TTF-1 nuclear staining is typically positive in lung and thyroid cancers. Approximately 68 of adenocarcinomas and 25 of squamous cell lung cancers stain positive for TTF-1 which helps differentiate a lung primary tumor from metastatic adenocarcinoma in a pleural effusion the mediastinum or the lung parenchyma. Distinguishing pleural mesothelioma from lung adenocarcinoma can be challenging. Calretinin Wilms tumor gene-1 WT-1 and mesothelin have been suggested as useful markers for mesothelioma. Gross cystic disease fibrous protein-15 a 15-kDa monomer protein is a marker of apocrine differentiation that is detected in 62-72 of breast carcinomas. UROIII high-molecular-weight cytokeratin thrombomodulin and CK20 are the markers used to diagnose lesions of .