Measurement of tumour height and base diameter in choroidal melanoma. Comparison between ultrasonography and histology

Abstract

Maximum tumour height and base diameter were determined in a series of 41 choroidal melanomas both in vivo using two-speed ultrasonography (1550 and 1660 m/sec) and on histological preparations using an optical microscope with an ocular micrometer. Tumour base was measured as the chord of a circle. The mean interval between ultrasonography and surgical enucleation was 15 ± 9 days (range: 1 to 48 days).

The mean histological tumour height was 6.9 ± 3.1 mm as compared to a ultrasonographically measured mean height of 8.3 ± 3.1 mm at the speed of 1550 m/sec (p < 0.05) and of 8.9 ± 3.4 mm at the speed of 1660 m/sec (p < 0.01). The mean tumour base measurement obtained histologically was 10.8 ± 3.7 mm, versus ultrasound mean values of 12.6 ± 3.5 mm at the speed of 1550 m/sec (p < 0.05) and 13.5±3.8 mm at 1660 m/sec (p < 0.01).

There was a good correlation between ultrasonographic and histological measurements at both speeds of sound both as regards tumour height (r = 0.88; p < 0.001) and as regards tumour base diameter values (r = 0.85; p < 0.001).The use of two different speeds of sound may account for maximum differences in tumour measurements not exceeding 0.9 mm, whereas the difference between histological and ultrasonographic measurements ranged from 1.7 to 2.9 mm.