E-cadherin, N-cadherin, and calretinin in pleural effusions: The good, thebad, the worthless

The distinction between reactive mesothelial cells (RMC), malignant mesothe lioma (MM), and metastatic adenocarcinoma (ACA) in pleural effusions may be impossible based on morphology alone, E-cadherin, N-cadherin, and calretin in ai-e newly described immunocytochemical markers, which can potentially b e utilised for facilitating this distinction. E-cadherin and N-cadherin ai- e calcium-dependent intercellular adhesion molecules expressed in epithelia l cells and mesenchymal/mesothelial cells, respectively The differential ex pression of E-cadherins in epithelial cells and N-cadherins in mesothelial cells has been utilized to differentiate reactive mesothelial cells, MMs an d ACAs. Calretinin is a calcium-binding protein within the family of EF-han d proteins. It is abundantly expressed in peripheral and central nervous ti ssues, and has been shown to consistently immunoreact with mesothelial cell s, We studied cell block sections from 77 pleural effusions (22 RMC, 26 MM, and 29 ACA) to investigate the potential immunocytochemical, use use of an ti-E-cadherin?, anti-N-cadherin and anti-calretinin antibodies for differen tiating between RMC, MM, and ACA in pleural effusions. A modified avidin-bi otin peroxidase complex (ABC) method was used E-cadherin immunostaining was observed in 14% of RMC, 46% of MMs, and 97% of ACAs. A distinct membrane s taining pattern was seen in ACAs. The pattern of staining was cytoplasmic i n all reactive RMC and varied from membrane to cytoplasmic in MMs. Anti-N-c adherin immunoreacted with 77% of RMC, 35% of MMs, and 48% of ACAs, Twenty- seven percent of RMC, 58% of MMs, and 31% of ACAs immunoreacted with anti-c alretinin. Based on these results, rye conclude that anti-E-cadherin is a p otentially useful marker in the distinction of ACA cells om RMC. However it is nor as useful for rite distinction of ACA and MM. Anti-N-cadherin and a nti-calretinin did not reliably distinguish between reactive mesothelial, M M, and ACA cells in pleural effusions. Published 1999 Wiley-Liss, Inc.(dagg er).