Mucocele: The majority of these lesions arise from the frontal or ethmoidal sinuses and extend into the orbit through expansion and erosion of bone. the precipitating problem is blocked sinus excretory ducts. Mucocels often displace the eye down and out and are filled with thick mucus material. Imaging study. Surgical resection with obliteration of the sinus with fat is often required. Mucoceles are lined with respiratory epithelium. Back to Orbit