Antigenic and cellular heterogeneity of primary uveal malignant melanomas
L. A. Donoso, J. A. Shields, J. J. Augsburger, J. Whitman and V. Arbizo
Monoclonal antibody (MAb) MAb8-1H, which identifies an ocular
melanoma-associated antigen, and computer-assisted cytomorphometric
analysis were used to investigate antigenic and cellular heterogeneity in
four atypical cases of choroidal or ciliary body melanoma. The presence of
one or more well-localized, morphologically distinct areas within each
uveal melanoma, suggestive of multiple tumor cell populations, was observed
by conventional light microscopy. In one choroidal melanoma with an unusual
bilobed configuration, MAb8-1H bound only to the anterior lobe composed of
spindle melanoma cells. In the other three cases, MAb8-1H bound selectively
to discrete regions within the uveal melanoma corresponding to the
well-localized, morphologically distinct areas seen by light microscopy. In
each case, a computer was used to calculate the nuclear area of 50 tumor
cells corresponding to the areas binding or not binding MAb8-1H. In three
of the four cases examined, the differences in mean nuclear area between
the discrete populations of tumor cells were statistically significant. Our
results suggest that some uveal melanomas are composed of two or more
discrete populations of tumor cells with regard to both expression of
melanoma-associated antigens and cytomorphologic features.
