Emperipolesis: An Unreported Novel Phenomenon in Oral Squamous Cell Carcinoma.

Emperipolesis is a phenomenon characterized by engulfment of hematopoietic cells by megakaryocytes, monocytes, fibroblasts, and malignant cells within their cytoplasm. This phenomenon has been reported in various physiological and pathological conditions including malignancies. However, emperipolesis has never been reported in oral squamous cell carcinoma (OSCC) till date. We have analyzed histopathological slides of 56 cases of OSCC to see lymphocyte engulfment by tumor cells. Five cases showing features of this phenomenon were observed. Lymphocytes were typically identified as small round cells with oval nuclei and scanty cytoplasm. Both partial and complete engulfment of lymphocytes by tumor cells was appreciated. Nuclei of the host tumor cells were crescent shaped and illustrated small concave indentation, so as to accommodate the internalized lymphocyte. The intercellular bridges were not seen between the internalized cell and the host cell. There were no signs of degeneration appreciable in either cell, thus ruling out the possibility of cannibalism phenomenon. Although emperipolesis is a well-known phenomenon in pathology, this is the first report showing its evidence in OSCC.