Identification and significance of multinucleate tumor cells in retinoblastoma

M. A. Howard, T. P. Dryja, D. S. Walton and D. M. Albert
David G. Cogan Eye Pathology Laboratory, Harvard Medical School, Boston, MA.

Multinucleate tumor cells were observed in a case of a retinal tumor suspected to be a retinoma (retinocytoma). On electron microscopy, these cells had characteristics of retinoblastoma. Similar cells were observed in an irradiated model of retinoblastoma grown in a nude mouse. We suggest that the presence of these cells indicates differentiation and/or regression of the tumor.