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.