Retinal pigment epithelium:
When adenocarcinomas and adenomas grow within the eye, they typically arise from a part of the retina called the retinal pigment epithelium (but can also occur in the ciliary body). Benign adenomas are much more common, since less than 20 adenocarcinomas of the RPE have ever been documented. This cancer has never been found to spread to other parts of the body (if there is no spread outside of the eye prior to treatment). 

Almost all RPE adenocarcinomas were clinically diagnosed as atypical choroidal melanomas and the eyes were enucleated. In a recent review of the literature, RPE adenocarcinomas were found to be more common in females, more likely to cause intraocular inflammation (atypical for choroidal melanomas), and respond poorly to radiation therapy.

Symptoms
Patients with adenomas of the retinal pigment epithelium typically have no symptoms. These tumors are found during routine eye examination and referred to eye tumor specialists for further evaluation. In the rare case of adenocarcinoma of the retinal pigment epithelium, patients were more likely to be female, experience intraocular inflammation and loss of vision.

Diagnosis
Retinal adenoma and adenocarcinoma will appear black. They originate from the retina, so they are not likely to have a surrounding or overlying retinal detachment. Adenomas appear dark on fluorescein angiography. 

Ultrasound may be helpful in distinguishing adenoma and adenocarcinoma of the RPE from uveal melanomas. Consider that they tend to arise from the retina above Bruch's membrane. They appear to be stuck on rather than growing from the choroid. Several investigators have noted a tuberous rather than collar-button or dome-shape. 


Treatments
Retinal adenoma should be photographed, measured by ultrasound and followed for evidence of growth prior to consideration of treatment. 

In the rare instance of retinal adenocarcinoma, most patients have been enucleated with a presumed diagnosis of choroidal melanoma. Should adenocarcinoma of the retinal pigment epithelium be suspected, a fine-needle biopsy should be considered. Remember, this patient is more likely to be a female presenting with a dark intraocular tumor associated with iritis and/or uveitis.