Plunging ranula intruding into the parapharyngeal space treated with OK-432.

We report a very rare case of a plunging ranula extending into the parapharyngeal space, which was treated successfully with OK-432. A 27-year-old woman presented with a 4-month history of right submandibular swelling. Based on computed tomography and magnetic resonance imaging findings, we established a diagnosis of plunging ranula intruding into the parapharyngeal space. The patient was treated with an intracystic OK-432 injection that was administered under ultrasonographic guidance. At 6 weeks after the injection, computed tomography showed complete disappearance of the cystic mass. No recurrence was noted during the 10-month follow-up.