Intraneural nerve metastasis with multiple mononeuropathies

Melanoma metastasis to the femoral nerve: a novel case of melanoma masquerading as mononeuropathy. Illustrative case

BACKGROUND

Metastatic cancer may involve the central and peripheral nervous system, usually in the late stages of disease. At this point, most patients have been diagnosed and treated for widespread systemic disease. Rarely is the involvement of the peripheral nervous system the presenting manifestation of malignancy. One reason for this is a proposed "blood-nerve barrier" that renders the nerve sheath a relatively privileged site for metastases.

OBSERVATIONS

The authors presented a novel case of metastatic melanoma presenting as intractable leg pain and numbness. Further workup revealed concurrent disease in the brain and breast, prompting urgent treatment with radiation and targeted immunotherapy.

LESSONS

This case highlights the rare presentation of metastatic melanoma as a mononeuropathy. Although neurological complications of metastases tend to occur in later stages of disease after initial diagnosis and treatment, one must remember to consider malignancy in the initial differential diagnosis of mononeuropathy.

Plexus and peripheral nerve metastasis

Cancer in the form of solid tumors, leukemia, and lymphoma can infiltrate and metastasize to the peripheral nervous system, including the cranial nerves, nerve roots, cervical, brachial and lumbosacral plexuses, and, rarely, the peripheral nerves. This review discusses the presentation, diagnostic evaluation, and treatment options for metastatic lesions to these components of the peripheral nervous system and is organized based on the anatomic distribution. As skull base metastases (also discussed in Chapter 14) result in cranial neuropathies, these will be covered in detail, as well as cancers that directly infiltrate the cranial nerves. Particular emphasis is placed on the clinical, imaging, and electrodiagnostic features that differentiate neoplastic plexopathies from radiation-induced plexopathies. Neurolymphomatosis, in which malignant lymphocytes invade the cranial nerves, nerve roots, brachial and lumbosacral plexuses, and peripheral nerves, is a rare manifestation of lymphoma and leukemia. Diagnoses of neurolymphomatosis are often missed or delayed given its varied presentations, resulting in poorer outcomes. Thus this disease will also be discussed in depth.

Neuromuscular complications in cancer

Cancer is becoming a treatable and even often curable disease. The neuromuscular system can be affected by direct tumor invasion or metastasis, neuroendocrine, metabolic, dysimmune/inflammatory, infections and toxic as well as paraneoplastic conditions. Due to the nature of cancer treatment, which frequently is based on a DNA damaging mechanism, treatment related toxic side effects are frequent and the correct identification of the causative mechanism is necessary to initiate the proper treatment. The peripheral nervous system is conventionally divided into nerve roots, the proximal nerves and plexus, the peripheral nerves (mono- and polyneuropathies), the site of neuromuscular transmission and muscle. This review is based on the anatomic distribution of the peripheral nervous system, divided into cranial nerves (CN), motor neuron (MND), nerve roots, plexus, peripheral nerve, the neuromuscular junction and muscle. The various etiologies of neuromuscular complications - neoplastic, surgical and mechanic, toxic, metabolic, endocrine, and paraneoplastic/immune - are discussed separately for each part of the peripheral nervous system.

Interfascicular Renal Cell Carcinoma Metastasis to the Ulnar Nerve: A Case Report

BACKGROUND

Metastatic solid tumors to the hand and peripheral nerves are exceedingly rare independent occurrences. Their occurrence together has never been reported in the literature.

METHODS

We present a case report of a 69 year old male with a previous history of renal cell carcinoma (RCC) presenting with a rapidly-growing painful mass located at the right volar ulnar wrist, found to have endoneural solid tumor metastatic RCC to the ulnar nerve.

RESULTS

Preoperative MRI imaging of the wrist revealed a heterogeneous mass on the volar aspect of the wrist extending along the length of the ulnar artery and nerve to the level of Guyon's canal. Pathologic examination of an incisional biopsy of the mass was consistent with metastatic renal clear cell carcinoma cells, which were infiltrating nerve and surrounding soft tissue. The patient underwent local radiation therapy to the wrist and hand with interval decrease in size of the mass and symptom improvement.

CONCLUSION

Solid tumor metastasis, although exceedingly rare, must be considered in the differential diagnosis of a patient with previous cancer history presenting with a wrist or hand mass associated with peripheral neuropathy.

Cancer around the brain

BACKGROUND

Neuro-oncologists are familiar with primary brain tumors, intracerebral metastases meningeal carcinomatosis and extracerebral intracranial tumors as meningeoma. For these conditions, and also some other rare tumor entities several treatment options exist. Cancer can also involve structures around the brain as the dura, the base of the skull, the cavities of the skull and tissue around the bony skull, the skin, the tissue of the neck. and either compress, invade or spread in the central or peripheral nervous system.

METHODS

A systematic literature research was conducted determining symptoms and signs, tumor sites of nerve invasion, tumor types, diagnostic techniques, mechanisms of nerve invasion, and important differential diagnosis. Additional cases from own experience were added for illustration.

RESULTS

The mechanisms of tumor invasion of cranial nerves is heterogenous and not only involves several types of invasion, but also spread along the cranial nerves in antero- and retrograde fashion and even spread into different nerve territories via anastomosis. In addition the concept of angiosomas may have an influence on the spread of metastases.

CONCLUSION

In addition to the well described tumor spread in meningeal carcinomatosis and base of the skull metastases, dural spread, lesions of the bony skull, the cavities of the skull and skin of the face and tissue of the neck region need to be considered, and have an impact on therapeutic decisions.

Renal carcinoma relapse presenting as a peripheral nerve sheath tumor: A case report and brief review of the literature

We report a rare case of renal carcinoma metastasis involving a lumbar nerve root. Metastases to nerve roots are rare occurrences, and to our knowledge, only six cases have been reported so far in the literature. The patient in this report presented with weakness in the right lower limb and intractable pain irradiating along the L5 dermatome. MRI findings revealed a right-sided L5 nerve root mass, suggestive of a schwannoma, involving the spinal ganglion and its extraforaminal region. Complete macroscopic resection of this mass was performed, and histopathologic analysis confirmed the lesion to be a metastasis of a renal clear cell carcinoma. Local radiotherapy was given and tyrosine kinase inhibitors administered. At 5 months, the patient was pain-free and his right limb weakness had completely resolved. A tumoral recurrence could be observed on the control MRI 5 months after surgery. This report presents the first case of a patient with a renal clear cell carcinoma metastasis to a L5 nerve root, as well as a brief review of previous cases of metastases to peripheral nerve roots.

Primary lung carcinoid, a rare cause of paraparesis: report of a case and review of the literature

Carcinoids are neuroendocrine tumors mainly involving the gastrointestinal tract, lungs and bronchi. They were considered benign with slow growth, but they can be malignant in a substantial percentage of patients (metastasizing to liver, bones, skin, etc). Endocrine activity results in carcinoid syndrome. Proximal myopathy has been reported in 7% of patients with carcinoid syndrome. Bronchopulmonary and thymic carcinoids producing adrenocorticotropic hormone can cause Cushing's syndrome, a main feature of which is myopathy. There are a few reports of carcinoids associated with paraneoplastic neurological syndromes, including neuropathy. We hereby present an extremely rare case of a primary lung carcinoid presented with paraparesis due to polyneuropathy, and review the relevant literature. To the best of our knowledge there is no similar previous report. Complete resolution of paraparesis after excision of the lung carcinoid suggests paraneoplastic neurological syndrome.

Malignant cell infiltration in the peripheral nervous system

The peripheral nervous system can be affected by malignancies involving different mechanisms. Neoplastic nerve lesion by compression, invasion, and infiltration is rare and occurs in particular in leukemia (neuroleukemiosis) and lymphoma (neurolymphomatosis). Its occurrence is much rarer in cancer, and even less so in sarcoma. The neoplastic infiltration of peripheral nerves by solid tumors is characterized by specific topographical sites such as the base of the skull, the ear, nose and throat region, and the cervico-brachial plexus as well as the lumbar and sacral plexus. Rarely malignant invasion affects the cranial nerves of the face where it can spread centripetally. Autonomic nerves and ganglia can also be affected. The retrograde spread of cancer in nerves is a bad prognostic sign. The clinical diagnosis is determined by tumor type, the pattern of involvement, and often pain.

Neuromuscular complications

Although direct neoplastic involvement of muscle tis-sue is surprisingly rare, considering the large amount of body mass that is represented by muscle tissue, the most important and unresolved muscle effect is muscle cachexia.Other associations, such as inflammatory, paraneo-plastic, toxic, and several extremely rare associations,have been described. Drug-induced toxicity and radiation recall syndrome need to be taken into consideration when muscle symptoms appear in patients with cancer.

Peripheral nervous system involvement in patients with cancer

Involvement of the peripheral nervous system (PNS) is common in patients with cancer and any part, including motor neurons, sensory ganglia, nerve roots, plexuses, cranial and peripheral nerves, and neuromuscular junctions, can be affected. Different mechanisms can initiate damage associated with cancer-related PNS disorders. These include tumour infiltration, toxicity of treatments, metabolic and nutritional perturbations, cachexia, virus infections, and paraneoplastic neurological syndromes. The type of cancer, lymphoma, or solid tumour is a further determinant of a PNS disorder. In this Review we discuss the different causes and mechanisms of disorders of the PNS in patients with cancer and we will focus on their assessment and diagnosis.

Endoneural metastasis of the sciatic nerve disclosing the relapse of a renal carcinoma, four years after its surgical treatment

METHODS

To report on an exceptional case of renal metastasis. Indeed, endoneural metastases of peripheral nerves are thought to be exceptional, and such an event has not yet been ascribed to a renal carcinoma.

RESULTS

We report on a sciatica leading to the discovery of a tumour of the right thigh which proved to be an endoneural metastasis of the sciatic nerve from a renal carcinoma surgically removed 4 years before.

CONCLUSION

A thorough palpation of peripheral nerve can help recognise such metastases in patients previously diagnosed with renal carcinoma.

Metastases to the peripheral nervous system

Cancer metastasis can affect any part of the nervous system. When the peripheral nervous system is involved, the usual targets are cranial nerves, nerve roots and plexi. However, peripheral nerves and muscles can also be affected by compression or infiltration of neoplastic cells. This review focuses in the diagnosis and treatment of metastatic complications of cancer involving plexi, peripheral nerves and muscles.

Nerve tumors of the hand and upper extremity

Tumors of peripheral nerve origin are usually slow growing and minimally symptomatic, making differentiation from other soft tissue neoplasms difficult. Yet failure to recognize a nerve tumor may result in irreversible loss of neurologic function. This article provides current information on the history, pathologic identification, and treatment of upper extremity nerve tumors. Other neoplastic and tumor-like lesions that occur within the peripheral nerve are also considered.