A 22-year-old woman presented with an acute compressive optic neuropathy due to a ruptured ethmoido-orbital mucocele. She underwent urgent orbital decompression and drainage of the mucocele via an endoscopic approach. Postoperatively, her course was complicated by an orbital compartment syndrome supervened, exhibiting severe eyelid edema caused by infiltration with mucin and mucin-containing macrophages (“muciphages”). Biopsy of the eyelid showed infiltration with “muciphages,” macrophages laden with extravasated mucinous material. This is the first report that documents the clinical and histopathologic course of orbital inflammation following mucocele extravasation into the orbit and eyelids.