Phakomatous choristoma of lower eyelid. A lenticular anlage tumour.

A female infant was found to have a congenital, firm, pea-sized tumour nasally in the lower left eyelid. A dermoid cyst was suspected, but microscopy showed structures simulating a lens. The tumour has been considered to have an origin in surface ectoderm induced to dip down into the mesoderm of the lid, there forming lenticular anlage structures. This so-called phakomatous choristoma has only been reported five times previously, all cases outside Europe.