Locally invasive tumors arising from hyperplasia of the retinal pigment epithelium

Purpose: Focal hyperplasia of the retinal pigment epithelium (RPE) is a com mon fundus condition that is generally stationary, with little or no tenden cy 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 tumo r of the RPE was documented to arise from a small focus of hyperplasia of t he RPE. Methods: Clinical and cytopathologic observations of two patients. Results: Both patients were observed for approximately 25 years with an unu sual progressive fundus tumor that originally arose from a small, flat, irr egular focus of hyperplasia of the RPE. The originally observed pigmented l esion was attributed to toxoplasmosis in one patient and laser treatment fo r central serous chorioretinopathy in the other. In both patients, the tumo r enlarged, invaded through the full-thickness sensory retina, and produced a characteristic retinal perforation with apposition of the mass to the vi treous. In both instances, fine-needle aspiration biopsy showed scant pigme nted cells, but a definite diagnosis was not made. However, clinical observ ations 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 h ave unique clinical features that differentiate them from uveal melanoma an d other pigmented fundus lesions.