A general histopathology report was provided by one veterinary pathologist, and a more extensive analysis was performed by another. (journals.plos.org)
Tumors of the adrenal gland in Dr. Christopher Fletcher's Diagnostic Histopathology of Tumors, 4th Edition, p 1294 (philmaffetone.com)
They probably sent it out for histopathology examination by a pathologist which will tell you even more accurately whether the margins were clean. (1800petmeds.com)