Hybrid peripheral nerve sheath tumor of parapharyngeal space having features of neurofibroma and schwannoma in an 8-year-old child – A rare entity

Tumors of the parapharyngeal space (PPS) are extremely rare inpediatric age group. Out of all head-and-neck neoplasms, PPS tumors comprise only 0.5%. Majority of neoplasms in poststyloid PPS are neurogenic tumors. Conventional benign peripheral nerve sheath tumor (PNST) includes neurofibromas, schwannomas and perineuriomas. Hybrid PNSTs are rare entities having combined features of more than one histologic type, and the World Health Organization Classification of Tumors of the Central Nervous System, in the latest 2016, 4 th edition, has recently recognized and published it. The most common hybrid tumor is schwannoma/perineuroma followed by neurofibroma/schwannoma and neurofibroma/perineuroma. Here, we are reporting a hybrid PNST which was completely excised and having combined features of neurofibroma and schwannoma, confirmed by both histopathologically and immunohistochemically, in an 8-year-old child, in PPS.