Neuroepithelial tumor of the retina in a dog

ANIMAL STUDIED: At routine vaccination a tumor in the right eye of a Golden Retriever was diagnosed.

PROCEDURE: The eye was enucleated, fixed in formalin and processed according to routine paraffin technique. Standard histologic, histochemical and immunohistochemical stainings were applied. Formalin-fixed tissue was used for electron microscopic examination.

RESULTS: The tumor originated from the retina and was composed of two different morphologic parts, a retinoblastoma-like part of small neuroepithelial cells and a medulloepithelioma-like part of columnar cells arranged in cords.

DISCUSSION AND CONCLUSION: It is discussed whether the tumor had its origin in different clones or in one clone, and it is suggested that the double differentiation might be the result of a transformation of retinal cells, demasking stem cell-like potentials.