Hybrid nerve sheath tumor

Hybrid nerve sheath tumors are uncommon, and most commonly encountered in the setting of neurofibromatosis type 1 or neurofibromatosis type 2. They represent benign peripheral nerve sheath tumors with combined histological features. The recognized combinations are :

• schwannoma + perineurioma (usually sporadic)
• schwannoma + neurofibroma (usually in the setting of NF1 or NF2)
• neurofibroma + perineurioma (rare, usually in the setting of NF1)

Hybrid nerve sheath tumors usually arise from peripheral nerve sheath tumors, rarely seen involving cranial nerves or spinal nerves .