Pathological Condition of the Retinal Pigment Epithelium: Neoplasms and Nodular Non-neoplastic Lesions

Eleven primary neoplasms of the retinal pigment epithelium (RPE) were studied histopathologically. These tumors presented a variety of histologic patterns, namely mosaic, tubular, papillary, or a patternless arrangement of vacuolated or anaplastic cells. The tumor with the mosaic pattern was regarded as best differentiated, the anaplastic tumor the least differentiated, and the tumors with vacuolated cells or tubular or papillary patterns in the middle of the spectrum. Such tumors invaded the retina and choroid, but metastasis was not observed. These neoplasms were contrasted with six nodular reactive proliferations of RPE, one of which approached neoplasia. Histologic criteria for differentiation of neoplasia from reactive proliferation are discussed. The available clinical data on tumors of the RPE and on reactive lesions are analyzed and compared.