Osseous choristoma of the choroid simulating a choroidal melanoma. Association with a positive 32P test
A. T. Williams, R. L. Font, H. J. Van Dyk and F. T. Riekhof
We report the clinical and histopathologic features of an osseous
choristoma of the choroid that appeared in a 26-year-old woman. Her
diagnostic evaluation included a radioactive phosphorus (32P) uptake test,
which was 270% positive and led us to believe that the lesion was an
atypical malignant melanoma. The extent of true ossification within this
tumor, seen microscopically, explains the false-positive uptake of
radioactive phosphorus by this benign tumor; it is well known that bone
avidly accumulates radioactive phosphorus. We recommend that all "atypical
choroidal melanomas" be studied for the presence of bone, with bone-free
roentgenograms, ultrasonography, and possibly, computerized tomographic
scans before 32P testing or enucleation. This, to our knowledge, is the
second histopathologically proved case of an osseous choristoma of the
choroid to be reported in the literature.
