Primary adenocarcinoma of the orbit initially diagnosed as idiopathic sclerosing orbital inflammation.

Purpose: Differentiating idiopathic sclerosing orbital inflammation from orbital inflammation secondary to neoplasia may be challenging, as both processes can present similarly. Neoplasms in the orbit may induce inflammation with accompanying fibrosis. Limited sections of histopathological specimens may demonstrate nonspecific inflammation and lead to an inaccurate diagnosis.

Observations: The authors present a case of infiltrating adenocarcinoma of the orbit with mucinous features which was misdiagnosed as idiopathic sclerosing orbital inflammation due to three separate benign biopsy specimens.

Conclusions And Importance: The ophthalmologist must remain suspicious of malignancy in cases of suspected idiopathic orbital inflammation with an atypical clinical course, regardless of apparently benign biopsy results.