Extensive Emperipolesis of Neoplastic Lymphocytes by Mesothelial Cells in Pleural Effusion Cytology in a Case of a Mediastinal T-Cell Lymphoblastic Lymphoma: A Rare but Diagnostically Useful Phenomenon

Abstract

Emperipolesis is a rare cell-in-cell phenomenon and a pathognomonic sign of Rosai-Dorfman disease. • Nonspecific lymphocyte rich pleural benign effusions are relatively common and mainly composed of reactive T lymphocytes. Novel Insights• Emperipolesis of lymphocytes by mesothelial cells is a rare finding that seems to be specific to both Band T-cell lymphomas in the context of lymphocyte rich pleural effusion. AbstractEmperipolesis is a biological process defined by the presence of an intact cell within the cytoplasm of another cell. In pleural fluid cytology, the phenomenon is very rare but has already been described in B-cell lymphoma. Here, we report the first case of a T-cell lymphoma diagnosed on a pleural fluid exhibiting extensive emperipolesis of tumor cells by mesothelial cells. Additionally, in order to evaluate the prevalence of emperipolesis in lymphocyte rich pleural effusion cytology, we reviewed cases from our archive, including cases with lymphoma and cases with reactive T-lymphocyte rich effusion.

Emperipolesis of lymphocytes by mesothelial cells in pleural effusion involved by T‐lymphoblastic lymphoma

“…Our case showed occasional giant multinucleated mesothelial cells with emperipolesis, while other reported cases exhibited extensive lymphocyte emperipolesis by mesothelial cells in pleural effusion lymphomas 4‐7 . This variation may reflect the stage or duration of the disease or may indicate different mesothelial cell‐lymphocyte cell interaction depending on the type of the lymphoma, its immunoprofile and surface receptors.…”

“…Lymphoid pleural effusion fluids can be benign inflammatory infiltrates or due to lymphomas. 5,8 Pleural effusion is a common manifestation of leukemias and lymphomas usually as single dispersed neoplastic cells. 8 Few cases of pleural effusion lymphomas with emperipolesis have been reported.…”

“…8 Few cases of pleural effusion lymphomas with emperipolesis have been reported. [5][6][7] Emperipolesis is an interaction between "guest" cells commonly granulocytes, plasma cells, and lymphocytes, and host cells usually histiocytes and other cells such hematopoietic cells and malignant cells. 3 Emperipolesis should be differentiated from phagocytosis and cannibalism.…”

“…Pleural effusion is a common manifestation of leukemias and lymphomas usually as single dispersed neoplastic cells 8 . Few cases of pleural effusion lymphomas with emperipolesis have been reported 5‐7 . Emperipolesis is an interaction between “guest” cells commonly granulocytes, plasma cells, and lymphocytes, and host cells usually histiocytes and other cells such hematopoietic cells and malignant cells 3 .…”

“…The best example is Rosai‐Dorfman disease (RDD), but it has been described in other tumors, hematopoietic diseases, and rarely in lymphomas 1‐4 . Its occurrence in effusion fluids is rare with few cases have been reported in the literature 5‐7 . We report a case of pleural effusion involved by mediastinal T‐lymphoblastic lymphoma with emperipolesis of the lymphocytes by giant multinucleated mesothelial cells.…”