Background & objective: To evaluate usefulness of immunohistochemical marker C-kit (CD117) in differentiating Adenoid cystic carcinoma (AdCC) from Polymorphous low-grade adenocarcinoma (PLGA) in patients of salivary gland carcinomas. AdCC is a malignant salivary gland neoplasm with poor prognosis. PLGA is a salivary gland malignancy with indolent growth pattern. Differentiating between the two entities is a diagnostic challenge. We evaluated the role of C-kit in differentiating the two.
Methods: This is a Cross sectional study. Samples of 19 tumors including 12 AdCC and 4 PLGA was evaluated at Department of Histopathology, Armed Forces Institute of Pathology, Rawalpindi from December 2015 to August 2016. Immunohistochemical techniques were used to analyze the level of c-kit expression in AdCC (n = 12), polymorphous low-grade adenocarcinoma (PLGA) (n = 6). Samples were stained using monoclonal antibody against C-kit. Statistical analysis of the data was done using SPSS version 21.
Results: Strong diffuse cytoplasmic reactivity was observed in more than 50% of the tumor cells of AdCC whereas less than 20% of cells showed negative to weak positivity in PLGA. Hence, the difference in the expression of c-kit between AdCC and PLGA was statistically significant (p value <0.002).
Conclusions: CD117 expression itself can be used as a marker in differential diagnosis of salivary gland neoplasms. However, the percentage of the CD117 immunoreactive cells and the staining intensities appeared to be important factors in distinguishing AdCC from PLGA.
Keywords: Adenoid cystic carcinoma; C-kit; Polymorphous low-grade adenocarcinoma; Salivary gland neoplasm.