Walsh & Hoyt: Choristomas of the Optic Disc, Nerve, and Chiasm

In addition to epidermoids and dermoids, several forms of choristomas of the visual apparatus may occur. Willis et al. reported 26 cases of heterotopic adipose tissue and smooth muscle in a colobomatous optic disc. All cases were unilateral, and in all but one case the affected eye was known or thought to have been blind since birth. The remaining case was that of a 13-year-old boy who experienced progressive loss of vision in one eye from 20/40 at age 7 to 20/200 by age 13. In all cases, enucleation of the affected eye was performed for cosmetic reasons, painful glaucoma, or fear of an underlying tumor. The pathologic findings in all cases included enlargement of the proximal region of the optic nerve, corresponding to a localized colobomatous defect in the optic disc. In addition, there was striking lipomatosis of the leptomeninges of the proximal optic nerve, combined with heterotopic smooth muscle in the peripapillary sclera and choroid, in the region of the coloboma.