Neoplasms of the retinal pigment epithelium: the 1998 Albert Ruedemann, Sr, memorial lecture, Part 2.

BACKGROUND Neoplasms of the retinal pigment epithelium (RPE) are rare, and little is known about their clinical variations, clinical course, and prognosis. Although most are benign, they can simulate choroidal melanoma. OBJECTIVES To evaluate the clinical characteristics, management, pathological features, and prognosis of acquired neoplasms of the RPE (adenoma and adenocarcinoma) and to define clinical features that help differentiate them from uveal melanoma. PATIENTS AND METHODS The medical records of patients with acquired tumor of the RPE were reviewed retrospectively, and the clinical features, management, and histopathologic findings were studied. RESULTS Of 13 affected patients, 10 were women and 3 were men. Ten were white and 3 were African American. The mean age at diagnosis was 53 years (range, 28-79 years). All patients were referred with the diagnosis of suspected choroidal melanoma. All tumors were solitary, unilateral, and ranged from a small, asymptomatic lesion measuring 2 x 2 x 1 mm to a massive neoplasm that measured 17 x 17 x 17 mm. There was no predilection for retinal location or laterality. The tumors were dark brown to black in 11 patients and only minimally pigmented in 2. Prominent retinal feeder vessels were visualized in 8 patients, 5 of whom had an exudative retinal detachment. Two patients had recurrent vitreous hemorrhage. Transillumination generally revealed blockage of light by the tumor. Fluorescein angiography showed early hypofluorescence and late minimal hyperfluorescence of the tumor, without visibility of choroidal vessels. Ultrasonography typically demonstrated the tumor to be abruptly elevated and to have medium to high internal reflectivity and acoustic solidity. Results of diagnostic fine needle aspiration biopsy, performed on 4 patients, disclosed cells compatible with a pigment epithelial origin. Treatment ultimately included observation in 4 patients, enucleation in 3, local tumor resection in 3, irradiation in 2, and laser therapy in 1. Microscopic verification of the diagnosis was available in 3 eyes after fine needle aspiration biopsy, 3 eyes after local resection, 3 eyes after enucleation, and 1 eye post mortem. The microscopic diagnosis was adenoma in 8 patients and adenocarcinoma in 2. Microscopically, the lesions were composed of a neoplastic proliferation of RPE cells. Tumors arising from the anterior portion of the RPE had a vacuolated pattern, and those in the posterior portion of the RPE had a glandular or tubular configuration. CONCLUSIONS Neoplasms of the RPE show considerable clinical variation. In contrast to melanoma, they generally are darker, more abruptly elevated, and more likely to have retinal feeder vessels and exudative retinal detachment; show early hypofluorescence and mild late hyperfluorescence on angiographic findings; and have high internal reflectivity on ultrasonographic findings. Although most acquired tumors of the RPE are benign cytologically, they can exhibit aggressive clinical behavior.