Prognostic role of cell morphology of animal tumors

The purpose of this presentation is to determine the prognostic role of cellular morphology in animal neoplasia. With some exceptions, cellular morphology is the single most accurate predictor of the prospective behavior of neoplasms. There is generally a positive correlation between the degree of malignancy and prognosis. The exceptions are a) morphologically malignant-appearing tumors following a benign course (e.g., canine histiocytoma, canine seminoma, equine sarcoid) and b) morphologically differentiated tumors exhibiting an unpredictable prognosis (e.g., canine pericytoma, acanthomatous epulis, myxoma, follicular thyroid cell carcinoma, etc.). Anaplasia, an important characteristic of most malignant neoplasms, may be less stable than generally assumed. Sodium butyrate may reverse it intermittently and anaplastic gliomas may loose all morphologic and cytokinetic characteristics of anaplasia following sodium butyrate exposure. Host factors, such as nerve growth factor, have similar and more lasting effects upon anaplastic cells derived from the neural crest. Such factors may act as reverse transformation agents and may represent prospective therapeutic agents for anaplastic tumors.