They can look like anything on the outside—they can be flat or raised, they can be hairless or haired, they can be cutaneous or subcutaneous. You really can’t look at a mass and say, “Yup, that’s a mast cell tumor!”
My patient had come in for a mass removal. On the outside, it looked like a lipoma and felt like a lipoma, and the owner just wanted the mass taken off. We came up with a plan to do an FNA and then surgery with histopathology. I asked the surgery resident, why FNA if you’re just going to take it off? She said, “What if you remove the mass, submit it for histopathology, and find out it’s a mast cell tumor and you didn’t get clean margins?”
So, we did an FNA on the mass, and what do you know—it was a mast cell tumor! I kind of think the resident is psychic, but that is still TBD. One thing that is great about fourth-year is getting to see real cases and put what you learn into action. It’s hard to remember the biological behavior, treatment, surgical excision protocols, grading system, and prognosis associated with mast cell tumors all just from the classroom. But seeing this patient, the information really sticks, and I will never forget this case. If it looks like a lipoma and feels like a lipoma, you can still stick a needle in it and look at it under a microscope to be sure!