Balck lab- mast cell tumor

Question
Our 18 month old black lab had a rapidly growing lesion under his left eye.  We had it excised two weeks ago.  The biopsy came back "mast cell tumor", and the vet said "he got it all", so I'm assuming the margins are negative.  I haven't been able to find out anything else about it.  Will it recur?  Thanks, Elaine Eustis, M.D. (gynecology!)

Answer
Solitary mast cell tumors generally cause no problems.  However, in a young dog any new lesions should be biopsied and identified.  If mast cell tumors become multiple or they are generalized, the release of histamine and other vasoactive substances can have some profound effects.