I just wanted to check if Histiocytoma when first appearing can not be red as shown in the picture below ? And if they are known for ulcerating the next day ? Also can a mast cell tumour do both those thing also ? I edited the lighting of the picture so it stand out more. I also added a picture of what it looked like a week later after the scab got knocked off and a picture closer to what it look like now. My dog a staffy aged 8.