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[Echographic study of the structure of a malignant melanoma of the choroid].

The case of a 74 yr. old male affected by a mixed cell choroidal melanoma is reported. Ophthalmoscopic examination suggested a choroidal melanoma; this diagnosis was confirmed by fluorescein angiography, ultrasonography and CT-scan. In particular, contact ultrasonography (A-mode and B-mode), following topographic, kinetic and quantitative diagnostic criteria, revealed a solid lesion with the typical features of a choroidal melanoma. Ultrasonography by differential selective echographic technique revealed that the lesion consisted of two components with different acoustic features : the first characterized by a 41 dB reflectivity (peripheral and superior portions), the second by a 23 dB reflectivity (central and inferior portions). Attenuation values were 1.2 dB/mm and 0.7 dB/mm, respectively. CT-scan did not show any significant change in density within the mass. Histopathologic evaluation confirmed a clear-cut edge between the epitheloid and the spindle-cell components. The more reflecting lesion (23 dB), located in the central-inferior portion of the lesion, was histologically less dense and was due to the epitheloid component. The superiorally located more attenuating lesion (1.2 dB/mm) was histologically more dense and due to the spindle-cell component.