However, cytology is no substitute for histopathology, as only the latter has been correlated with prognosis. Two systems of histopathologic grading have been defined, and to avoid confusion, it is essential to know which of the 2 systems is being used. Although there is believed to be a benign variant of canine mast cell tumor, there is no clinical or microscopical means of identifying it. In addition, small mast cell tumors may remain quiescent for long periods before becoming aggressive. Thus, all should be treated as malignancies.
Treatment depends on clinical stage of the disease.
If histological evaluation suggests that the tumor extends beyond the surgical margins, additional surgery or, arternatively, radiation therapy should be initiated. At present there is no agreed upon mode of therapy for Stage II-IV mast cell tumors. For Stage II tumors, several options are available including excision, prednisolone, and radiotherapy used either singly or in combination. Treatment of Stage III and IV tumors is generally palliative. In addition, cimetidine may also have some antitumor activity.