Spontaneously regressing retinoblastomas, retinoma, or retinoblastoma group 0.

A 5-year-old boy had a gray, translucent retinal mass containing calcified nodules and surrounded by retinal pigment clumping and atrophy. The eye was enucleated and the patient has remained well for seven years. Microscopic examination disclosed an intraretinal tumor composed of benign-appearing cells in a bed of well-vascularized ground substance with calcific foci. There was surrounding retinal pigment epithelial hyperplasia but no peripheral necrosis or signs of tumor regression. There were no mitoses, cellular pleomorphism, nuclear atypia, rosettes, or other characteristics of malignancy. Tumors with this typical fundus appearance have been termed spontaneously regressing retinoblastoma or retinoma. Although the tumor in this patient was histopathologically benign, it carries the same genetic risk as a retinoblastoma. A better term for this lesion, therefore, is retinoblastoma group 0.