Extravascular papillary endothelial hyperplasia arising from parapharyngeal space.

A 66-year-old man visited our clinic suffering from swelling of right pharyngeal space. He was not aware of other symptoms. The contrast CT showed patchy enhancement with calcification. The enhanced MRI revealed a non-homogeneous signal pattern and patchy central enhancement. During surgery, egg-shaped hard elastic tumor was observed in parapharyngeal space without any sign indicating an invasion into surrounding nerves or feeding vessels. Then the tumor was removed without significant hemorrhage or damage to the cranial nerve. Histological examination of the tumor revealed a nodular lesion with blood clot and hematoma encapsulated with fibrous tissue having vascular spaces of irregular shape and size. From those findings, the tumor was diagnosed as papillary endothelial hyperplasia (PEH). However, since the location of the tumor differed from that of PEH commonly observed in the intravascular space, the tumor was classified as extravascular PEH.