Peripheral nerve sheath tumor

Last revised by Ciléin Kearns on 3 Nov 2024

Peripheral nerve sheath tumors (PNSTs) are a group of primary neurogenic tumors that arise from nerve sheaths outside of the central nervous system. The vast majority are benign, however, malignant transformation is seen particularly in large tumors and those associated with neurofibromatosis type 1 (NF1).

Symptoms of benign peripheral nerve sheath tumors are non-specific and include sensory and/or motor deficits, isolated pain, painful mass (i.e. positive Tinel sign), asymptomatic mass or may be incidental 12.

Many peripheral nerve sheath tumors express somatostatin receptors 6.

Their imaging appearances, demographics, treatment, and prognosis vary greatly, and these are discussed separately.

The WHO classification of tumors of soft tissues recognizes a variety of peripheral nerve sheath tumors:

Ultrasound or MRI, the latter considered gold-standard, may suggest a neurogenic origin of a soft tissue mass and whether there are benign or malignant features, however, in most cases, imaging cannot reliably distinguish between the different histological subtypes 9.

Usually, a presumptive diagnosis is made taking into account patient demographics, pre-existing conditions (e.g. neurofibromatosis type 1 or type 2), the location and size of the tumor, and evidence of rapid growth.

Shared imaging features are discussed below.

As a group, localized peripheral nerve sheath tumors demonstrate the following features:

Surgical resection is the treatment of choice, not only for diagnostic confirmation (i.e. histopathology) and also with curative intent 9.

Pre-surgical biopsy of peripheral nerve sheath tumors (usually an ultrasound-guided core biopsy) is typically reserved for lesions with indeterminate or malignant clinical and/or radiological features; the risk of biopsy (e.g. new/worsening neuropathic pain or sensory/motor impairment) outweighs the benefit of biopsy in suspected benign peripheral nerve sheath tumors 10,11.

Considerations include 7,8: