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 prog nosis. Although most are benign, they can simulate choroidal melanoma. Objectives: To evaluate the clinical characteristics, management, pathologi cal features, and prognosis of acquired neoplasms of the RPE (adenoma and a denocarcinoma) and to define clinical features that help differentiate them from uveal melanoma. Patients and Methods: The medical records of patients with acquired tumor o f the RPE were reviewed retrospectively, and the clinical features, managem ent, and histopathologic findings were studied. Results: Of 13 affected patients, 10 were women and 3 were men. Ten were wh ite and 3 were African American. The mean age at diagnosis was 53 years (ra nge, 28-79 years). All patients were referred with the diagnosis of suspect ed choroidal melanoma. All tumors were solitary, unilateral, and ranged fro m 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 locat ion or laterality. The tumors were dark brown to black in II patients and o nly minimally pigmented in 2. Prominent retinal feeder vessels were visuali zed in 8 patients, 5 of whom had an exudative retinal detachment. Two patie nts had recurrent vitreous hemorrhage. Transillumination generally revealed blockage of light by the tumor. Fluorescein angiography showed early hypof luorescence and late minimal hyperfluorescence of the tumor, without visibi lity of choroidal vessels. Ultrasonography typically demonstrated the tumor to be abruptly elevated and to have medium to high internal reflectivity a nd acoustic solidity. Results of diagnostic fine needle aspiration biopsy, performed on 4 patients, disclosed cells compatible with a pigment epitheli al origin. Treatment ultimately included observation in 4 patients, enuclea tion in 3, local tumor resection in 3, irradiation in 2, and laser therapy in I. Microscopic verification of the diagnosis was available in 3 eyes aft er fine needle aspiration biopsy, 3 eyes after local resection, 3 eyes afte r enucleation, and 1 eye post mortem. The microscopic diagnosis was adenoma in 8 patients and adenocarcinoma in 2. Microscopically, the lesions were c omposed of a neoplastic proliferation of RPE cells. Tumors arising from the anterior portion of the RPE had a vacuolated pattern, and those in the pos terior 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, an d more likely to have retinal feeder Vessels and exudative retinal detachme nt; show early hypofluorescence and mild late hyperfluorescence on angiogra phic findings; and have high internal reflectivity on ultrasonographic find ings. Although most acquired tumors of the RPE are benign cytologically, th ey can exhibit aggressive clinical behavior.