A-scan ultrasonography in the diagnosis of orbital dermoid cysts.

Eleven patients with anterior and deep orbital masses had A-scan ultrasonography. The ultrasonograms were all similar and demonstrated a dermoid-like pattern of low internal reflectivity and a high-rising, double-peaked posterior surface spike. Although the postoperative pathologic findings in seven cases confirmed the clinical diagnosis of dermoid cyst, other lesions, such as epidermoid cyst, sebaceous cyst, Graves's myopathy, and Ewing's sarcoma were found to show a similar ultrasonographic pattern. This stresses the importance of computed tomography in the diagnosis of orbital tumors.