Overview.
Mesenteric malignant nerve sheath tumors are less common malignant tumors that originate from the Schwann cell peripheral nervous system, also known as malignant Schwann cell tumors. This tumor is most often caused by malignant transformation of a neurofibroma or nerve sheath tumor. Mesenteric malignant nerve sheath tumor grows within or adjacent to the nerve trunk and is seen as an ovoid or spindle-shaped mass, large and well defined, with an incomplete envelope. The tumor is nodular or lobulated, soft, homogeneous, grayish-white or purplish-red, often with hemorrhagic necrosis and cystic or mucinous degeneration. It is easy to recur after resection and grows rapidly, and a small part of it metastasizes to local lymph nodes and hematogenous metastasis to the lungs. Malignant nerve sheath tumors are often combined with multiple neurofibromatosis, and a few patients may be combined with malignant tumors of non-neural origin.
Etiology
Malignant nerve sheath tumors of the mesentery are mostly formed by malignant transformation of plexiform neurofibromas.
Symptoms
The clinical manifestations of mesenteric malignant nerve sheath tumor vary with the size and location of the tumor. When the tumor is small, it may be asymptomatic. Larger tumors may cause paresthesia or pain symptoms due to compression of nerves, accompanied by radiating pain. The typical manifestation of ultrasonography is a round, homogeneous hypoechoic mass with clear boundary, obvious peripheral peripheral echogenicity, rich blood supply, and often enhancement effect in the posterior part, which may not be homogeneous when the tumor has hemorrhage, necrosis or cystic degeneration.
Examination
1. Ultrasound
Ultrasound typically shows a round, homogeneous hypoechoic mass with clear boundary, obvious peripheral echoes, rich blood supply, often with enhancement effect at the back, when the tumor is hemorrhage, necrosis or cystic degeneration, the echoes may not be homogeneous.
2.CT
Computed tomography (CT) examination is generally difficult to diagnose malignant nerve sheath tumor. Scanning only shows isolated or diffuse mass, with different sizes, part of which has peripheral echoes, and the edges can be smooth and flat or fuzzy, and the central area of the tumor can be seen as flaky low-density shadow, and the enhancement shows plaque, grid or island-like enhancement, and the low-density area is not enhanced.
3. Magnetic resonance imaging
Generally, it shows inhomogeneous signal, cystic degeneration is common, target sign is rare, and there is inhomogeneous and significant enhancement in the enhancement.
Diagnosis
In addition to clinical manifestations, CT examination is generally more difficult to diagnose malignant nerve sheath tumor, and the scanning only shows isolated or diffuse mass, with different sizes, part of which has envelope, and the edge can be smooth and flat or fuzzy, and the central area of the tumor can be seen as flaky low-density shadow, and the enhancement is plaque, grid, or island-like enhancement, with no enhancement of the low-density area.MRI generally shows uneven signal, cystic degeneration is common, and the target sign is rare, and the enhancement is not uniform and significant enhancement. The enhancement is uneven and significant. Emission computed tomography (ECT) is valuable in identifying primary or metastatic tumors. Neurosphincter tumors with low-density areas, non-smooth and flat tumor borders, uneven enhancement of the solid part of the lesion, and infiltration of the lesion into the surrounding tissues are the characteristics of malignant neurogenic tumors. Pathologic examination is the “gold standard” for the diagnosis of malignant nerve sheath tumor.
Differential diagnosis
1. Other tumors originated from mesentery.
2. mesenteric cysts, hematoma.
3. Soft tissue tumors originating from retroperitoneum.
4. Metastatic tumors originating from other intra-abdominal organs.
Treatment
The treatment of mesenteric malignant nerve sheath tumor is preferred to a combination of surgery, including radiation therapy and chemotherapy. Surgical resection is the most effective treatment method. Because the tumor of this disease mostly grows within or beside the nerve trunk and involves a section of nerve tissue, it is difficult to determine the margin of the tumor, frozen section should be made at the upper and lower margins of the involved nerve segment during surgery. Low-grade malignant superficial tumors can be cured by wide excision, while highly malignant tumors involving larger nerve trunks can be removed or amputated. External irradiation of the tumor alone is often insensitive, requiring higher doses of radiation and greater adverse effects. The efficacy of chemotherapy is uncertain.