Mesothelial cells Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Mesothelial cells and links to relevant pages within the course.
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|Synovial Lining Cells|
A joint space has a membranous lining similar to the mesothelium found in the pleural and peritoneal cavities. The synovial lining cells, which make up this membrane, produce synovial fluid which lubricates the joints.In a normal joint there is a minimal total volume of fluid present. With joint trauma, such as infection or inflammation, the volume will be increased and synovial lining cells may be noted on the cytospin preparation in addition to the cell types normally present with infection, inflammation or hemorrhage. Synovial lining cells (see arrows) resemble miniature mesothelial cells or small macrophages. They can be found singly or in clumps and can have "foamy"-looking cytoplasm.
|Synovial Lining Cells|
In the image on the right, a clump of synovial lining cells (see arrow) is pictured. This slide originated from a patient with rheumatoid arthritis.Observe the size of these synovial lining cells relative to the lymphocytes and neutrophil present in the picture. They are smaller than mesothelial cells found in other fluids.Notice the fluffy, foamy appearance to the cytoplasm. While these cells are found in a cluster, it is still possible to make out indistinct cytoplasmic boundaries. Just like mesothelial cells, these may occasionally be bi-nucleate.
|Adenocarcinoma in Peritoneal Fluid|
This is a cytospin of an ascites fluid from a patient with widely metastatic adenocarcinoma.Notice the size of these tumor clumps (see arrows) when compared to the size of the background neutrophils, lymphocytes and macrophages.Also, note how close together the nuclei appear in the tumor clump. Think about the separation you would see in a mesothelial clump. These tumor cells are larger than mesothelial cells would normally be. They have a considerably larger and more dysplastic-looking nucleus and have much less cytoplasm than a mesothelial would normally have. These are key differentiating features in the identification of adenocarcinoma tumor clumps in fluids.
|Neuroblastoma Tumor Clump vs. Mesothelial Clump in Pleural Fluid|
This photo shows a neuroblastoma tumor clump (blue arrow) in the same field as several mesothelial cells (red arrows).While the individual cells are the same overall size, the tumor cells have larger nuclei and a smaller amount of cytoplasm than the mesothelial cells. The chromatin is finer in these tumor cell nuclei. Also, note the differences in the mesothelial cell chromatin pattern, which is much more coarse in texture with darker nucleoli present. The mesothelial cells have a distinct demarcation between adjacent cells, while this line of demarcation is not as apparent in the sheet of tumor cells.
|Metastatic Tumors in Fluid Cytospins.|
There are a wide variety of solid tumors that can metastasize and spread into body fluids. As with cytospins positive for leukemia or lymphoma, any smear with tumor or suspected tumor should be sent for pathology or hematologist review.Body fluids tend to be a good growth medium for metastatic tumors. These tumor cells tend to be present in sheets and clumps. Frequently there will be reactive changes with increased mesothelial cells and macrophages associated with metastatic tumors as well.Tumor cells, in general, typically appear large with fine/open chromatin patterns, dismorphic or dysplastic nuclei and prominent nucleoli. They will have varying amounts of basophilic cytoplasm depending on the tissue of origin.
|Select the specific cells listed below that can be found in all types of body fluid.||View Page|
|Match the following blood cell types to the respective body fluids where they may reside.||View Page|
The mesothelium is the name given to the membrane that lines most body cavities and surrounds the internal organs. Cells that shed from these membranes are commonly found in pleural, peritoneal and pericardial fluids. Mesothelial cells are large cells that may be found as single cells or in clusters and clumps. They tend to have a large round centrally placed nucleus with a generous amount of basophilic cytoplasm which can appear frayed at the edges. They will have one ore two small, well-defined, deeply staining nucleoli. While they may have small pinpoint vacuoles, they will not have the larger "foamy" vacuoles seen in macrophages or histocytes.There are two mesothelial cells in the image below (see arrows). While they are different in size, they are definitely larger than the background lymphocytes and plasmacytoid lymphocytes. Notice the irregular frayed edge to the cytoplasmic membrane.
|Reactive Mesothelial Cells|
Reactive mesothelial cells can be found when there is an infection or an inflammatory response present in a body cavity. This condition can be due to the presence of a bacterial, viral or fungal infection. It can also be the result of trauma or the presence of metastatic tumor.Reactive mesothelial cells tend to come in clusters and clumps and have a more washed out cytoplasm in body fluids. Notice in the image on the right, how indistinct the cytoplasmic borders are in this clump compared to normal mesothelial cells. The wide separation of the nuclei and the well defined nucleoli help to identify these as reactive mesothelial cells. However if there is any doubt, the smear should be sent for hematology or pathology review.Note: It is not uncommon for macrophages to be mixed into a reactive mesothelial clump.
|Mesothelial Cells continued|
Mesothelial cells are frequently found in clusters and clumps. In Image 1 below, the individual cells in this clump still maintain the round nuclus and generous basophilic cytoplasm that can be seen in individual mesothelial cells. Also, the boundaries between cells are clear and distinct, unlike a multinucleate histiocyte in which there are no clear boundaries between the previously discrete cells. In this particular image, there are two binucleate mesothelial cells in this mesothelial clump.Binucleate mesothelial cells are a normal variant found in any fluid with mesothelial cells. Rarely trinucleate mesothelial cells can be seen. However, any fluid that has mesothelial cells with more than 3 nuclei is abnormal and should be sent for hematology or pathology review. Image 2 depicts binucleate mesothelial cells.