Twelve histochemical methods; affinity staining with
avidin peroxidase,
wheat germ agglutinin, and concavalin-A
agglutinin; and an immunohistochemical
stain with Kp1 (CD68) antibody were compared for their relative effectiveness in staining canine mast cell
tumors. Stains were compared in 28 mast cell
tumors and 19
histiocytomas. The effectiveness of the histochemical methods and the
lectins decreased as the mast cells became less differentiated. None of the staining methods were positive on
histiocytomas.
Periodic acid-Schiff (PAS) gave positive results in a few cases of mast cell
tumors where other histochemical stains were negative. Although
avidin peroxidase and Kp1 antibody stained more mast cell
tumors than any other method, they did not differ significantly from Luna's method,
toluidine blue pH 0.5,
toluidine blue pH 4.5,
alcian blue pH 2.5,
safranin O, Unna's method, and Giemsa. No
stain was ideal for the diagnosis of canine mast cell
tumors; however, this study suggests that the use of
avidin peroxidase, Kp1 antibody, and PAS may give additional information for individual poorly differentiated
tumors without substantial increase in time or cost.