Desmoplastic fibroma (DF) is a benign intra-osseous neoplasm characterized by the formation of abundant collagen fibers. It arises most commonly in the jaws and exhibits local aggressiveness and high recurrence rates after local resection. An uncommon case of expansive DF involving the right maxilla, maxillary sinus, and inferior orbital wall of a 49-year-old man whose initial symptoms were similar to acute sinusitis is presented, and the criteria for diagnosis and clinical management are discussed.1166E510E513