NEUROSARCOMA (MPNST)

Neurosarcomas, or now commonly known as malignant peripheral nerve sheath tumor (MPNST) are also known as malignant peripheral nerve sheath tumors, malignant schwannomas, and neurofibrosarcomas, are rare.⁴ They develop from Schwann cells or pluripotent cells of the neural crest and occur mainly in adults. They can arise anywhere in the body, including the upper extremity, but are uncommon in the hand. Most patients with a MPNST tumor are between 20 and 50 years of age and preset with a complaint of an enlarging mass.  The male/female ratio is approximately 50:50.  Pain complaints are variable.  Only 3-10% of soft tissue sarcomas are malignant peripheral nerve sheath tumors.^2,3  Diagnosis and treatment are often delayed owing to the absence of symptoms or nonspecific symptoms. Most patients with sporadic neurosarcoma have no risk factors for the disease, but tumor growth is aggressive, and the prognosis is poor. On the other hand, patients with neurofibromatosis type 1 (NF-1) have a lifetime risk of developing an MPNST of 8-13%.³  The 2- and 5-year overall survival rates are 57% and 39%, respectively. In patients with rhabdomyosarcomatous differentiation, the 2- and 5-year survival rates are 15% and 11%, respectively.

Pathophysiology

• About 50–75% of neurosarcomas arise from neurofibromas, typically the plexiform type or in the setting of neurofibromatosis type I (NF1; von Recklinghausen disease) and tend to occur in the head and neck.
• Others arise de novo, usually involving the peripheral nerves of the buttocks or thighs.
• In ~15% of neurosarcomas, epithelioid or heterologous differentiation can be observed. Heterologous differentiation includes rhabdomyoblasts, smooth muscle, bone, cartilage, and neuroendocrine components.

Related Anatomy

• Neurofibrosarcomas are not well encapsulated; therefore, surgery cannot preserve the nerve.
• The lesion often extends through multiple compartments.
• Complete surgical excision with negative microscopic surgical margins improves survival and decreases the risk of local recurrence.³

Incidence and Related Conditions

• Peripheral nerve tumors comprise <5% of all tumors of the hand.
• Neurosarcomas are rare, occurring in only 0.001% of the population.
• Neurosarcomas account for 2–3% of malignant tumors of the hand.
• The typical age range for patients with neurosarcoma is 20–50 years.^1,2

Differential Diagnosis

• Chondrosarcoma
• Connective tissue diseases
• Fibrosarcoma
• Gall bladder cancer
• Ganglioneuroma
• Hematoma
• Hydatid cyst
• Liposarcoma
• Metastatic carcinoma
• Osteosarcoma
• Rhabdomyosarcoma
• Schwannoma, benign
• Soft-tissue sarcoma

The patient is likely to be 30–50 years of age, male or female, and presenting with the complaint of a painful lump. The physician should maintain a high degree of suspicion if neurofibromas are present or the patient has von Recklinghausen’s disease.

SURGICAL COMPLICATIONS

• Nerve damage
• Follow-up for several years is necessary to check for recurrence.
• Local recurrence may be accompanied by metastasis, possibly in the lungs, liver, or brain. 

• There is a 65% chance of tumor recurrence after surgery.
• There is a 40% chance of metastasis upon regrowth, most commonly to the lung. 
• S100 is a specific neural biomarker used to identify nerve sheath tumors; however, S100 is often negative in MPNST's.  Further, the absence of a positive S100 antigen marker is associated with an increased risk of metastasis and death from these malignant nerve tumors.³

• The patient with sarcoma of the upper extremity should be referred to a specialist multidisciplinary team for diagnosis and treatment.
• Patients may benefit from support groups, conferences with a counselor or therapist, and online support.
• A 1988 study of 24 patients who underwent wide, local excision for sarcoma of the forearm, wrist, or hand found minimal postoperative discomfort and a 91% survival rate at 44 months with good-to-excellent function.
• Many researchers believe that neurosarcoma is insensitive to radiotherapy and chemotherapy, as neither treatment has significantly alerted the course of the disease.

New Article

1. Angelopoulos E, Eleftheriou K, Kyriakopoulos G, et al. A giant intrathoracic malignant schwannoma causing respiratory failure in a patient without von Recklinghausen’s disease. Case Rep Med 2016;2016:2541290. PMID: 27118974
2. Stucky CCH, Johnson KN, Gray RJ, et al. Malignant peripheral nerve sheath tumors (MPNST): Mayo Clinic experience.  Ann Surg Oncol 2012; 19:878-885.
3. Zou C, Smith KD, Liu J, et al. Clinical, pathological and molecular variables predictive of maglinant peripheral nerve sheath tumor outcomes.  Ann Surg 2009; 249:1014-1022.
4. Tekaya R, Hamdi W, Bouaziz M, et al.  Cervicobrachial neuralgia revealing neurosarcoma.  Revue Neurologique 2008; 165(1):82-86.

Review

1. Guo A, Liu A, Wei L, Song X. Malignant peripheral nerve sheath tumors: differentiation patterns and immunohistochemical features. A mini-review and our new findings. J Cancer 2012;3:303-309. PMID: 22773934

Classics

1. Wexler AM, Eilber FR, Miller TA. Therapeutic and functional results of limb salvage to treat sarcomas of the forearm and hand. J Hand Surg Am 1988;13:292-6. PMID: 3351258
2. Strickland JW, Steichen JB. Nerve tumors of the hand and forearm. J Hand Surg Am 1977;2(4):285-91. PMID: 197148