"Anemone" Cell (Villiform) Tumors: Electron Microscopy and Immunohistochemistry of Five Cases

The authors are grateful to Gilbert C. Fischer, MD, Mona Ghobrial, MD, John C. Merenkov, MD, and Balbino B. Fernandez, MD for their contributions of case material to this study and to Hector Battifora, MD for performing the monoclonal anti-keratin antibody stains. Five large cell malignant neoplasms were studied by immunohistochemistry and electron microscopy. Ultrastructural examination demonstrated numerous circumferential microvilli in 3 cases and a more polarized distribution in 2 cases. The tumor cells in 2 cases demonstrated the surface glycoprotein T29/33, indicative of a hematopoietic neoplasm. Two cases (including one positive for T29/33) contained intracytoplas-mic IgG-kappa. Anti-keratin staining using both polyclonal and monoclonal antibodies was negative. Two patients are alive and in remission after treatment for lymphoma. One died with tumor following a progressive course, and one has been lost to follow-up. A fifth patient died of tumor and at autopsy was found to have a disseminated pancreatic tumor. Microvilli around large malignant cells have been commonly associated with epithelial tumors; however, our findings indicate that, in the absence of intercellular junctions and tonofilaments, the possibility of malignant lymphoma should be considered and pursued immunohistochemically.