THE ROLE OF IMMUNOHISTOCHEMISTRY FOR PRIMARY ORAL DIAGNOSIS IN A BRAZILIAN ORAL PATHOLOGY SERVICE.

This retrospective study was designed to determine the contribution of immunohistochemistry (IHC) in the primary diagnosis of oral diseases in one of the main services of oral pathology in the state of São Paulo, Brazil, as well as to identify the most common antibodies used and recommend algorithms based on our experience with controversial lesions. Among 27,677 cases received from 2007 to 2019, 371 cases required a total of 1549 immunohistochemical stains (1.3%). The most used antibodies were Ki-67, S-100, α-SMA, and CD34. Among the definitive diagnoses, 41.2% were malignant tumors, 52.3% benign, 1% lesions of uncertain malignancy, 2.7% premalignant, 2.4% reactive, and 0.2% inconclusive. Only a small percentage of cases required IHC and only 25.3% of IHCs performed were mandatory to reach the diagnoses. The inherent limitation of incisional biopsies was also cited as a reason for inconclusive diagnoses, despite a wide range of antibodies our laboratory displays. [ABSTRACT FROM AUTHOR]