A panoramic radiograph shows a discrete radiopaque calcified mass projecting into/over the maxillary sinus, often in a patient with a history of chronic sinusitis. This is best termed a(n):

An antrolith is a calcified mass that forms within the maxillary sinus (antrum), often around a nidus of mucus, blood clot, or foreign material, frequently in the setting of chronic sinus inflammation. A rhinolith is the nasal-cavity equivalent, and a sialolith forms within a salivary gland duct.