Lymphatic or venule (venule possible because a few erythrocytes are present) containing neoplastic embolus. Note mitotic figures within embolus !! This is one aggressive tumor. 40x H&E stain
This is a photomicrograph from a biopsy of a left axillary mass in a 7 year old Rat Terrier. This is undoubtedly a cutaneous metastasis from a tumor elsewhere in the body. I am recommending a search for a primary (lung or pancreas are possible primaries). Will definitely follow up if I have additional information.
I had such trouble picking out mitotic figures when I first started my research project… the highlight would be when I asked the PhD student if a eosinophil was a mast cell undergoing mitosis, dear God. Proud to say I can pick out the mitotic figures in this slide though!