Purpose: To describe CT scan findings following orbital exenteration in 27 patients and to identify the factors involved in the development of post exenteration hyperostosis.

Methods: Noncomparative case series. The authors reviewed the charts of 27 patients ranging in age from 33 to 99 years, who underwent unilateral exenteration at King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia and at the School of Medicine of Ribeirão Preto, University of São Paulo, Brazil. Data regarding patient demographics, surgical procedure, clinical diagnosis, and preoperative and postoperative CT imaging of the orbits were obtained. The relationship between hyperostosis and postoperative time, gender, age, adjuvant radiotherapy, and cavity coverage was evaluated by multivariate stepwise logistic regression.

Results: Seventeen (73.9 %) orbits had postoperative orbital hyperostosis. No soft tissue masses were detected in the affected orbits except in 2 cases with tumor recurrence. The only factor associated with hyperostosis was immediate intraoperative socket rehabilitation (odds ratio = 0.13, 95% confidence interval: 0.01–0.89). There was an 87.0% lower chance of hyperostosis in patients whose socket was covered with musculocutaneous flaps. Sequential CT scans showed that orbital hyperostosis followed a specific pattern. Initially, bone thickening appeared as either uniform or undulating endo-osteal minimal thickening along the roof and then on the lateral and medial walls. More advanced hyperostosis had a laminated/lamellated appearance progressing to homogeneous and diffuse circumferential bone thickening. New bone formation and bone overgrowth were late findings. Hyperostosis extended to involve the adjacent facial bone, more obviously on the maxilla. Some patients had minimal thickening of the adjacent frontal and squamous temporal bone. Over-pneumatization of the paranasal sinuses was evident in all cases of hyperostosis.

Conclusions: Development of hyperostosis following exenteration is not rare. Radiologists and surgeons should be aware of the need to monitor the orbital healing process closely to avoid misdiagnoses of tumor recurrence/radionecrosis or infection. Obliteration of the orbital cavity with musculocutaneous flaps significantly reduces the chances of bone hyperostosis.