Correlation Between Radiologic and Histopathologic Features of Orbital Epidermoid and Dermoid Cysts.

PURPOSE: Epidermoid cysts (EC) and dermoid cysts (DC) typically appear as well-circumscribed lesions on CT. This study aimed to clarify the radiologic and histopathologic characteristics of orbital EC and DC and to determine the correlations between them.

METHODS: The medical records of 69 patients who underwent surgery for orbital DC or EC at Samsung Medical Center between January 2001 and August 2016 were retrospectively reviewed. The size and location of the cysts, rim enhancement, homogeneity of contents, presence of hemorrhagic or calcific components, radiodensity of contents, and extent of bony remodeling were evaluated using CT. Additionally, the cyst lining and contents were examined histopathologically.

RESULTS: Among patients with orbital cysts, EC and DC were diagnosed in 10 (14.5%) and 59 (85.5%) patients, respectively. Further, 50.0% of EC and 79.7% of DC were located in the superotemporal quadrant of the orbit. On orbital CT, the average radiodensity of EC and DC was 18.9 ± 56.2 and -67.9 ± 63.3 HU, respectively. The cystic contents were more frequently homogeneous than heterogeneous in both EC and DC; however, the radiodensity of cysts differed significantly, which may be attributed to sebaceous gland activity. Focal bony notching, bone remodeling under pressure, and bony changes from dumbbell-shaped cysts were observed more frequently in DC than in EC.

CONCLUSIONS: Radiological and histopathological features are correlated in orbital EC and DC. Therefore, orbital EC and DC can be preoperatively differentiated using CT, based on the average radiodensity and bony remodeling.