What are the other Names for this Condition? (Also known as/Synonyms)

• Perineurial Cell Tumor

What is Perineurioma? (Definition/Background Information)

• Perineurioma is a rare tumor of the perineurial cells, a type of cells that are present around a peripheral nerve sheath
• These tumors are generally benign in nature, but may be occasionally malignant. Perineuriomas can occur at a superficial location (underneath the skin), or they may be deep-seated (affecting various internal organs)
• There are 3 different types of Perineuriomas, namely:
  • Intraneural Perineurioma: The tumor grows along the nerve; most commonly in the peripheral nerves of the arms and legs
  • Soft Tissue Perineurioma: When the tumor does not grow along the nerve, but instead, grows into the soft tissues surrounding a nerve, they are called Soft Tissue Perineuriomas. These tumors may be present at any location in the body
  • Malignant Perineurioma: It is the malignant transformation of a Perineurioma that can either be the intraneural type or soft tissue type
• There are no identified risk factors or causative factors for Perineurioma, though certain chromosomal abnormalities have been observed
• In majority of cases, Perineuriomas may present no signs and symptoms. And, these tumors may be only incidentally discovered, while performing radiological studies for other health reasons
• Benign Perineuriomas may not require any treatment, but may be monitored for growth and any malignant transformation. A complete surgical excision of such Perineuriomas is performed when necessary, which can be curative
• In case of malignancy, then a combination of chemotherapy, radiation therapy, and invasive procedures may be used to treat the tumors
• The prognosis is generally excellent for benign tumors that can be easily removed. However, the prognosis for malignant Perineurioma is based on the stage of the tumor and its location, apart from other factors

Who gets Perineurioma? (Age and Sex Distribution)

• Perineurioma can affect both adults and children (adolescents)
• Both males and females are affected
• There is no known racial, ethnic, or geographical preference

What are the Risk Factors for Perineurioma? (Predisposing Factors)

• The risk factors for the development of Perineurioma are currently unknown or unidentified

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Perineurioma? (Etiology)

• The exact cause of Perineurioma formation and tumor development is unknown
• Studies have shown chromosomal abnormalities on chromosome 22 (monosomy of chromosome 22)

What are the Signs and Symptoms of Perineurioma?

The signs and symptoms of Perineurioma depend on the location and type of the tumor (whether soft tissue, intraneural, or malignant type). The signs and symptoms may include the following:

• Perineuriomas may be observed at any location in the body
• Soft Tissue Perineuriomas may be seen as small, solitary tumors that do not cause any significant signs and symptoms
• Intraneural Perineuriomas may show enlargement of the affected nerve and muscle weakness
• The tumors may form anywhere in the body
• There may be pain in the affected region
• In individuals with Malignant Perineuriomas, loss of weight and appetite, and fatigue is observed. However, these symptoms appear later, as the cancer progresses

How is Perineurioma Diagnosed?

Perineuriomas are diagnosed using the following tools:

• Complete physical examination with comprehensive evaluation of medical history
• Radiographic studies of the affected region
• Tissue biopsy: A tissue biopsy is performed and sent to a laboratory for a pathological examination. The pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. The biopsy is generally performed to rule out other more severe conditions
• Molecular analysis to exclude other tumors
• If tumor has metastasized (into the lungs or other regions) then PET scan, bone scan, and chest x-rays may be taken

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Perineurioma?

There are no significant complications that occur due to benign Perineuriomas. Nevertheless, malignant tumors may present the following complications:

• Metastasis to other sites in the body
• Damage of vital nerves, blood vessels, and surrounding structures, during surgery to remove the tumor
• Side effects from chemotherapy (toxicity), radiation therapy
• Recurrence of the tumor in case of incomplete excision and removal

How is Perineurioma Treated?

Treatment measures for Perineurioma may include the following:

• In case of benign tumors:
  • If there are no symptoms, then periodic observation is maintained. If there is any pain, it can be controlled through pain medication
  • Surgical excision with removal of the entire tumor is undertaken, if the symptoms are severe. This is normally curative. A surgery may not be usually performed in many cases, since the risks for surgery may far outweigh the benefits
• In case of malignant tumors:
  • Any combination of chemotherapy, radiation therapy, and invasive procedures may be used
  • Embolization is used to provide temporary relief from the symptoms, and reduce blood loss during a surgical procedure
  • Wide surgical excision and removal of the entire tumor, followed by radiation therapy (or chemotherapy) is the standard treatment mode
• Post-operative care is important: One must maintain minimum activity levels, until the surgical wound heals
• Post-operative follow-up care with regular screening and check-ups are important

How can Perineurioma be Prevented?

Current medical research has not established a way of preventing Perineurioma.

What is the Prognosis of Perineurioma? (Outcomes/Resolutions)

• In many cases, Perineuriomas are asymptomatic and these tumors may not require any treatment. However, the healthcare provider may undertake regular monitoring of the tumor, which is important
• The prognosis is generally excellent, when the tumors are small, benign and are completely excised
• The prognosis of malignant type of Perineurioma depends upon the stage of the tumor, the location of the tumor, and the age and health of the individual

Additional and Relevant Useful Information for Perineurioma:

• When examined under a microscope, histologically, there are different types of Perineuriomas, which include:
  • Sclerosing Perineurioma (most common type)
  • Reticular Perineurioma
• A differential diagnosis may be considered to eliminate the following conditions:
  • Neurofibroma
  • Dermatofibroma
  • Neurothekeoma