Locally invasive tumors arising from hyperplasia of the retinal pigment epithelium

Purpose: Focal hyperplasia of the retinal pigment epithelium (RPE) is a common fundus condition that is generally stationary, with little or no tendency to enlarge or spawn neoplasms. The purpose of this report is to describe the unusual clinical features of two similar cases in which a nodular tumor of the RPE was documented to arise from a small focus of hyperplasia of the RPE. Methods: Clinical and cytopathologic observations of two patients. Results: Both patients were observed for approximately 25 years with an unusual progressive fundus tumor that originally arose from a small, flat, irregular focus of hyperplasia of the RPE. The originally observed pigmented lesion was attributed to toxoplasmosis in one patient and laser treatment for central serous chorioretinopathy in the other. In both patients, the tumor enlarged, invaded through the full-thickness sensory retina, and produced a characteristic retinal perforation with apposition of the mass to the vitreous. In both instances, fine-needle aspiration biopsy showed scant pigmented cells, but a definite diagnosis was not made. However, clinical observations in both patients suggested that these tumors were acquired neoplasms that arose from small foci of hyperplasia of the RPE. Conclusion: Focal hyperplasia of the RPE can give rise to unusual invasive tumors that invade and replace the overlying sensory retina. These tumors have unique clinical features that differentiate them from uveal melanoma and other pigmented fundus lesions.