Wright's stain, 100x

Wright's stain, 400x

Lipoma is a neoplasm that is both common (in the dog) and easy to diagnose cytologically. One of  the limitations of a diagnosis based on cytology for this tumor is the recovery of a sample that is sufficiently cellular since adipose tissue will not always readily adhere to a glass slide. When a sample is obtained by needle aspiration, one can note the presence of a clear, greasy or oily liquid, which doesn't appear to "dry." During staining, it is important to gently handle the specimen so that the cells are not rinsed off. Cells can also be stained with a drop or two of New Methylene Blue Stain and viewed immediately under the microscope instead of using a routine stain. Note that it is also possible to obtain subcutaneous adipose tissue when sampling other lesions, and that tissues such as lymph nodes commonly have abundant perinodal fat. Adipocytes are large, round cells, which contain a dense nucleus often located in the periphery of the cell.