Diagnosis of orbital mass lesions: clinical, radiological, and pathological recommendations.

The orbit can harbor mass lesions of various cellular origins. The symptoms vary considerably according to the nature, location, and extent of the disease and include common signs of proptosis, globe displacement, eyelid swelling, and restricted eye motility. Although radiological imaging tools are improving, with each imaging pattern having its own differential diagnosis, orbital mass lesions often pose a diagnostic challenge. To provide an accurate, specific, and sufficiently comprehensive diagnosis, to optimize clinical management and estimate prognosis, pathological examination of a tissue biopsy is essential. Diagnostic orbital tissue biopsy is obtained through a minimally invasive orbitotomy procedure or, in selected cases, fine needle aspiration. The outcome of successful biopsy, however, is centered on its representativeness, processing, and interpretation. Owing to the often small volume of the orbital biopsies, artifacts in the specimens should be limited by careful peroperative tissue handling, fixation, processing, and storage. Some orbital lesions can be characterized on the basis of cytomorphology alone, whereas others need ancillary molecular testing to render the most reliable diagnosis of therapeutic, prognostic, and predictive value. Herein, we review the diagnostic algorithm for orbital mass lesions, using clinical, radiological, and pathological recommendations, and discuss the methods and potential pitfalls in orbital tissue biopsy acquisition and analysis.