Hybrid peripheral nerve sheath tumours - A Review

Area of Science:

• Oncology
• Pathology
• Genetics

Background:

• Hybrid peripheral nerve sheath tumors (PNSTs) are complex neoplasms comprising combinations of neurofibroma, schwannoma, and perineurioma.
• First described in the 2013 WHO Classification of Tumors of Soft Tissue and Bone, these tumors present diagnostic challenges due to their varied histology.
• Common variants include perineurioma-schwannoma, while neurofibroma/schwannoma combinations are often associated with neurofibromatosis types 1 or 2.

Purpose of the Study:

• To provide a concise update on hybrid peripheral nerve sheath tumors.
• To highlight diagnostic challenges and recent molecular findings.
• To underscore the need for vigilance regarding their pathogenesis and clinical course.

Main Methods:

• Review of histopathology and immunohistochemistry for diagnosis.
• Analysis of molecular data, including gene fusions and mutations.
• Synthesis of current literature on hybrid PNSTs.

Main Results:

• Hybrid PNSTs are typically benign, dermal, or subcutaneous lesions.
• Novel findings include a CHD7-VGLL3 fusion gene in schwannoma-perineurioma and ERBB2 mutations in some neurofibroma/schwannomas.
• Molecular pathogenesis, recurrence, and malignant transformation risks remain largely uncharacterized.

Conclusions:

• Hybrid PNSTs require careful pathological evaluation and clinical monitoring.
• Emerging molecular insights offer potential avenues for understanding pathogenesis.
• Further research is crucial to elucidate the full spectrum of hybrid PNST behavior.