Ultrasound detection of posterior scleral bowing in young patients with choroidal melanoma

Background: In evaluating young patients with choroidal melanomas, which ar e uncommon in people less than 30 years old, we noted that some had the ult rasound appearance of posterior scleral bowing. The purpose of this study w as to determine the incidence of posterior scleral bowing in young patients with choroidal melanoma, Methods: We reviewed the ultrasonograms of 24 patients less than 30 years o f age (mean age 25 years [standard deviation (SD) 4.7 years]) who presented to an ocular oncology service in Toronto between May 1984 and May 1997. In all cases the diagnosis was choroidal melanoma, Histologic specimens were available in six cases, Results: Scleral indentation posterior to the normal curvature of the globe was identified in 14 patients (58%), These patients had a mean tumour heig ht of 4.4 mm (SD 2.0 mm) and mean tumour diameter of 9.5 mm (SD 2.9 mm). In the 10 patients with no scleral bowing the mean tumour height was 5.7 mm ( SD 3.1 mm) and mean tumour diameter 11.5 mm (SD 3.8 mm), Pathological study (results available in nine cases in the scleral bowing group and four case s in the group without bowing) showed that all the tumours in the former gr oup and three of those in the latter group were of the more indolent cell t ypes, either mixed with predominantly spindle cells, or spindle cell. The s ix patients with histologic specimens were all in the scleral bowing group, The histologic features supported the ultrasound finding of posterior scle ral bowing, No transscleral invasion occurred over the tumour region. Interpretation: Posterior bowing of the sclera at the tumour site was obser ved in over half of young patients with choroidal melanoma. This phenomenon can be detected by ultrasonography and has a different appearance from tha t of choroidal excavation.