Background: Most head & neck tumors are of squamous cell carcinoma type, with a high tendency for recurrence; Upregulation of programmed death ligand-1 (PDL-1) in some cancers associated with poor prognosis. Immunotherapy by using PDL-1 monoclonal antibodies to block this receptor on tumor cells is mainly used for metastasized, surgically unresectable, or recurrent cancers.

Aim: To assess the immunohistochemical expression of PDL-1 in head and neck tumors by the aid of H-score, and its relation to clinicopathological parameters and the staining pattern.

Methods: Thirty cases of head and neck tumors were collected randomly from March 2018 till July 2018 for Immunohistochemical staining of (PDL-1). The staining was assessed as either membranous or non-specific cytoplasmic/ membranous. Variable staining patterns were detected between normal squamous cells and tumor cells, besides; variable staining patterns between different areas within the tumor were also noticed. The t-test was performed for statistical analysis.

Results: There was a significant statistical difference between the mean percentage of squamous cell carcinoma cells for the non-specific staining patterns (p=0.022) and for the calculated H- index (p=0.004) with the tumor grade. When comparing the H-index of stained neoplastic cells and stained normal squamous cells, a significant statistical difference was noticed (p-value= 0.0019).

Conclusion: Immunohistochemical method for detection of PDL1 in head and neck squamous cell carcinoma shows variable results, with a significant relation between stained tumor cells and tumor grade, which can be used as a predictor to apply immune therapy.

Keywords: Head and neck tumors, PDL1 expression, staining patterns