Unilateral exophthalmos is often caused by lymphomas of the orbit. B-scan ultrasonographic examination demonstrates certain characteristic features of orbital lymphomas, facilitating their clinical diagnosis. These ultrasonic features include an irregular contour, a lobulated configuration, acoustic homogeneity, and definite acoustic solidity. The ultrasonic characteristics of orbital lymphomas correlate well with the pathologic characteristics of these tumors. Lack of encapsulation and diffuse spread in the orbit are typical of lymphomas and result in the irregular contour and lobulated configuration found on ultrasonic examination. Lymphomas are homogeneous, monotonously cellular tumors and are acoustically homogeneous. These tumors are solid masses and appear solid on ultrasonic examination.
Coleman DJ, Jack RL, Franzen LA. High Resolution B-Scan Ultrasonography of the OrbitIII. Lymphomas of the Orbit. Arch Ophthalmol. 1972;88(4):375-379. doi:10.1001/archopht.1972.01000030377004