Erythrophagocytosis by Undifferentiated Lung Carcinoma Cells

A case is reported of undifferentiated metastatic lung carcinoma in which both a supraclavicular lymph node and bone marrow were infiltrated by anaplastic tumor cells which had engulfed erythrocytes and nucleated elements. The possibility of a histiocytic origin for the phagocytizing neoplastic cells was excluded by ultrastructural, cytochemical, and immunoperoxidase studies. This investigation shows that epithelial tumor cells may, at times develop phagocytizing activity, a phenomenon observed in certain experimentally induced tumors. The mechanism responsible for this phenomenon is not clear.