title: Malignant transformation in a hybrid schwannoma/perineurioma: addition to the spectrum of a malignant peripheral nerve sheath tumor.
abstract: Benign nerve sheath tumors include schwannomas, neurofibromas and perineuriomas. The malignant counterpart of a nerve sheath tumor is designated as a malignant peripheral nerve sheath tumor (MPNST). Lately, benign nerve sheath tumors comprising more than one component have been described, including hybrid schwannomas/perineuriomas. However, malignant transformation in a hybrid schwannoma/perineurioma has not been documented so far. Herein, we present a rare case of a young adult male who presented with a soft tissue mass in his right thigh that was excised elsewhere and submitted to us for histopathological review. One of the tissue sections displayed histopathological features of a hybrid schwannoma/perineurioma, including alternate arrangement of benign schwann and perineurial cells, reinforced with S100-P and epithelial membrane antigen positivity, respectively, along with low MIB1 and negative p53 immunostaining. The other two tissue sections showed a spindly sarcomatous tumor that was immunohistochemically positive for S100-P, CD34, p53 and exhibited high MIB1 (30-40%). Diagnosis of a MPNST arising in a hybrid schwannoma/perineurioma was made. This unusual case forms yet another addition to the spectrum of a MPNST.
authors.affiliation: Department of Pathology, Tata Memorial Hospital, Mumbai, India. rekhi.bharat@gmail.com
authors.forename: Bharat
authors.initials: B
authors.lastname: Rekhi
authors.forename: Nirmala A
authors.initials: NA
authors.lastname: Jambhekar
mesh_terms: D000328:Adult; D018952:Antigens, CD34 / Q000032:analysis; D006651:Histocytochemistry; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008853:Microscopy; D018317:Nerve Sheath Neoplasms / Q000150:complications* / Q000175:diagnosis* / Q000473:pathology* / Q000601:surgery; D009442:Neurilemmoma / Q000150:complications* / Q000473:pathology* / Q000601:surgery; D009418:S100 Proteins / Q000032:analysis; D013848:Thigh / Q000473:pathology / Q000601:surgery; D016159:Tumor Suppressor Protein p53 / Q000032:analysis
chemical_list: D018952:Antigens, CD34; D009418:S100 Proteins; D016159:Tumor Suppressor Protein p53