Contemporary Profile of Hybrid Nerve Sheath Tumors: Clinical, Anatomical, and Imaging Characteristics.

Objective: Hybrid peripheral nerve sheath tumors (HPNSTs) are rare benign neoplasms combining features of more than one peripheral nerve sheath tumor subtype-most commonly schwannoma, neurofibroma, and/or perineurioma. Multicenter registry data were used to improve their clinical, radiological, histopathological, and syndromic characterization. Methods: This study analyzed 55 histologically confirmed HPNSTs in 52 patients from a multicenter registry of 627 surgically treated patients at four tertiary neurosurgical centers in Germany and Austria. Demographic, anatomical, clinical, imaging, histopathological, surgical, follow-up, and syndrome-associated variables were evaluated. Results: HPNSTs were identified in 52/627 surgically treated registry patients (8.3%), comprising 55 lesions. Median age at surgery was 57 years (IQR 44-63 years; range, 18-78), and 27/52 patients (51.9%) were female. Lower-extremity or lumbosacral lesions were more common than upper-extremity or cervicothoracic lesions (32 vs. 23 cases). Schwannoma/neurofibroma hybrid was the predominant subtype (51/55, 92.7%), followed by schwannoma/perineurioma and triphasic schwannoma/neurofibroma/perineurioma tumors (2/55 each, 3.6%). All tumors were benign. Provoked pain was the leading symptom (47/55, 85.5%), whereas motor deficits were uncommon (5/55, 9.1%). MRI frequently showed inhomogeneous contrast enhancement (42/48, 87.5%) and cystic components (19/47, 40.4%). Complete resection was achieved in 49/55 tumors (89.1%). A documented or suspected syndromic association was present in 18/52 patients (34.6%). Conclusions: In this surgically selected multicenter registry cohort, HPNSTs accounted for 8.3% of operated peripheral nerve tumor patients. This cohort frequency should not be interpreted as population prevalence. The integrated clinical, imaging, pathological, and surgical data highlight pain burden, multifocality, and potential syndromic associations. Long-term behavior cannot be determined because follow-up was short and incomplete.