Mixed radiopaque and radiolucent lesion of the maxillary sinus: a radiographic challenge.

This article describes 3 patients, each of whom presented with an asymptomatic mixed radiopaque and radiolucent lesion of the maxillary sinus associated with a nonvital tooth. Based on the radiographic findings, a diagnosis of a collapsed (ruptured) radicular cyst was rendered in each case. A tissue biopsy was performed in 1 case, and the results supported the diagnosis. The radiographic and histopathological features, etiology, pathophysiology, and radiographic differential diagnosis of this condition are discussed.