plexiform schwannoma

Plexiform Schwannoma: A Rare Variant of Peripheral Nerve Sheath Tumor

Plexiform schwannoma is a rare variant of schwannoma, a type of benign peripheral nerve sheath tumor. It is characterized by its unique growth pattern, which involves the multinodular or plexiform growth of Schwann cells within the nerve fascicles.

Key Features:

• Rare Variant: Plexiform schwannoma accounts for only 5% of all schwannomas [10].
• Multinodular Growth Pattern: The tumor grows in a multinodular or plexiform pattern, which can make diagnosis more difficult due to its similarity with other neural tumors [13].
• Intraneural Growth: Plexiform schwannoma involves the growth of Schwann cells within multiple nerve fascicles or a nerve plexus [10].
• Subcutaneous Location: These tumors often occur in the subcutaneous tissue and are rarely confined to the dermis [10].

Clinical Presentation:

Plexiform schwannomas typically manifest as solitary, slow-growing masses that may be painful or asymptomatic. They can occur in various locations, including the head, neck, upper and lower extremities, and posterior regions.

Diagnosis and Treatment:

The diagnosis of plexiform schwannoma is primarily based on histopathological examination and electron microscopy. Complete resection of the tumor is often challenging due to its multinodular growth pattern and involvement of multiple nerve fascicles [2]. However, surgical excision remains the primary treatment option for this rare variant of schwannoma.

References:

[1] Harkin et al. (1978) - First reported case of plexiform schwannoma in an abstract from the International Congress of the American Association of Neuropathologists. [2] Berg et al. (1993) - Series of 2,259 schwannomas, including 97 cases of plexiform schwannoma. [10] Description of plexiform schwannoma and its characteristics. [13] Case report of a 28-year-old woman with a solitary plexiform schwannoma of the great palatine nerve.

Plexiform schwannomas are rare variants of Schwann cell tumors that can cause a range of signs and symptoms, although many cases may be asymptomatic.

Common Signs and Symptoms:

• Painful swelling: Plexiform schwannomas can cause painful swelling in the affected area, which can be tender to touch.
• Numbness or tingling: The tumor can compress nearby nerves, leading to numbness or tingling sensations in the affected limb or region.
• Weakness or paralysis: In some cases, the tumor can cause weakness or paralysis of the affected muscle or group of muscles.

Less Common Signs and Symptoms:

• Hearing loss or ringing in the ears: Plexiform schwannomas can occur in the nerve that connects the brain to the inner ear, leading to hearing loss or tinnitus (ringing in the ears).
• Facial weakness or paralysis: The tumor can affect facial nerves, leading to weakness or paralysis of facial muscles.
• Other neurological symptoms: In rare cases, plexiform schwannomas can cause other neurological symptoms such as seizures, confusion, or changes in mental status.

Incidental Detection:

Many plexiform schwannomas are detected incidentally during a medical examination for another condition. They may be found on imaging studies such as MRI or CT scans, and further evaluation is usually necessary to confirm the diagnosis.

References:

• [6] A five-year-old girl presented with painful swelling in the affected area.
• [11] Plexiform Schwannomas are slow-growing tumors and a majority does not exhibit any significant signs and symptoms.
• [13] Most of these tumors develop in the skin or subcutaneous tissues of extremities, the head, neck, or trunk. Signs and symptoms of melanotic schwannoma are linked to tumor location.
• [14] The symptoms and signs of a schwannoma develop from direct effects on the main nerve or from the tumor pressing on nearby nerves, blood vessels or tissues.

Imaging Tests for Diagnosing Plexiform Schwannoma

Plexiform schwannomas can be diagnosed using various imaging tests, which help locate and confirm the presence of this type of tumor.

• Magnetic Resonance Imaging (MRI): MRI is a preferred imaging test for diagnosing plexiform schwannomas. It produces clear images of the organs and structures within your body, including tumors like plexiform schwannoma [3].
• Computed Tomography (CT) scans: CT scans can also be used to diagnose plexiform schwannomas, although MRI is generally preferred for its higher resolution [3].
• Ultrasound: Ultrasound imaging may also be used to diagnose plexiform schwannomas, particularly in cases where other tests are inconclusive.

Other Diagnostic Methods

In addition to imaging tests, other methods can be used to diagnose plexiform schwannoma:

• Biopsy for histological examination: A biopsy involves taking a sample of tissue from the tumor and examining it under a microscope. This can help confirm the diagnosis of plexiform schwannoma [15].
• Immunochemistry: Immunochemistry tests can also be used to diagnose plexiform schwannoma by analyzing the presence of specific proteins in the tumor cells.
• Ultrastructural studies with electron microscopy: These studies are mainly used for research purposes and involve examining the structure of the tumor cells at a microscopic level.

References

[3] CM Ieong · 2020 · Cited by 4 — Imaging examination of CT, ultrasound and MRI can clearly show the location and extent of tumor and its relationship with adjacent structures, thereby guiding ...

[15] There are several methods used to diagnose cutaneous schwannoma clinically, and they include ultrasonography, biopsy for histological examination, immunochemistry, in addition to ultrastructural studies with electron microscopy which are mainly used for research purposes.

Note: The above information is based on the search results provided.

Differential Diagnosis of Plexiform Schwannoma

Plexiform schwannoma, a rare variant of schwannoma, requires careful differential diagnosis to rule out other similar-looking skin lesions and tumors. The following conditions are considered in the differential diagnosis of plexiform schwannoma:

• Plexiform neurofibroma: This is a type of neurofibroma that can resemble plexiform schwannoma in appearance. However, it lacks the Antoni A and B pattern characteristic of schwannomas and is not encapsulated [4][14].
• Malignant peripheral nerve sheath tumors (MPNSTs): These are aggressive tumors that can arise from peripheral nerves and may show a plexiform growth pattern similar to plexiform schwannoma. However, they typically have a more infiltrative and destructive appearance on imaging studies [7][9].
• Neurofibromas: Specifically, the plexiform variant of neurofibroma can be considered in the differential diagnosis of plexiform schwannoma. However, neurofibromas typically have nerves coursing through the mass that can be demonstrated with immunohistochemical staining [14].
• Lymphatic malformation: This is a benign tumor that can arise from lymphatic vessels and may show a plexiform growth pattern similar to plexiform schwannoma. However, it typically has a more cystic appearance on imaging studies [7].
• Venous malformation: This is another type of benign tumor that can arise from venous vessels and may resemble plexiform schwannoma in appearance. However, it typically has a more vascular appearance on imaging studies [7].

Key Diagnostic Features

To differentiate plexiform schwannoma from these conditions, the following key diagnostic features are considered:

• Imaging studies: MRI is particularly useful in assessing the extent and characteristics of the tumor. CT scans may also be used to evaluate the tumor's size and location.
• Histopathology: A biopsy sample can be examined under a microscope to confirm the diagnosis of plexiform schwannoma. The presence of Antoni A and B patterns, as well as S100 positivity, are characteristic features of schwannomas [14].
• Immunohistochemistry: This technique can be used to identify specific markers that may help differentiate plexiform schwannoma from other conditions. For example, the absence of nerves coursing through the mass may suggest a diagnosis of neurofibroma rather than schwannoma [14].

Conclusion

In conclusion, differential diagnosis of plexiform schwannoma requires careful consideration of several conditions that can resemble it in appearance. By considering key diagnostic features such as imaging studies, histopathology, and immunohistochemistry, clinicians can accurately diagnose this rare variant of schwannoma.