Blockage of the main parotid duct, or one of its branches, is often a primary cause of acute parotitis, with further inflammation secondary to bacterial superinfection. The blockage may be from a salivary stone, a mucous plug, or, more rarely, by a tumor, usually benign. Salivary stones (also called sialolithiasis, or salivary duct calculus) are mainly made of calcium, but do not indicate any kind of calcium disorder.[3] Stones may be diagnosed via X-ray (with a success rate of about 80%[3]), a computed tomography (CT) scan or Medical ultrasonography.