Melanotic schwannoma

Malignant
melanotic nerve sheath tumor • Malignant melanotic nerve sheath tumor - Ganzer Fall bei Radiopaedia
Gaillard F, Malignant melanotic nerve sheath tumor. Case study, Radiopaedia.org (Accessed on 27 Mar 2023) https://doi.org/10.53347/rID-90016 • CC by-nc-sa 3.0 (modified)
Malignant
psammomatous melanotic schwannoma mimicking adrenal cyst: case report. Contrast-enhanced computed tomography (CT), venous phase, axial view
aops.springeropen.com • CC-by-4.0
Malignant
psammomatous melanotic schwannoma mimicking adrenal cyst: case report. A T2-weighted, coronal view. B T2-weighted, axial view. C Fat suppressed sequence, axial view. D Gadolinium enhanced T1, axial view. The formation shows strongly heterogeneous MR-characteristic, mainly cystic (T2-hyperintense) and with hemorrhagic content (T1-hyperintense); there is presence of a relatively thick capsule (possibly a pseudocapsule due to a highly thin and peripherally dislocated parenchyma) and fine septa. After application of contrast material, there is an amplification of the signal at the periphery (capsule/pseudocapsule) of the lesion and in the septa. Mass effect on the upper pole of the right kidney, right hepatic lobe, inferior vena cava, and right renal vein is present
aops.springeropen.com • CC-by-4.0
A para-aortic
malignant melanotic nerve sheath tumor mimicking a gastrointestinal stromal tumor: a rare case report and review of literature. Contrast-enhanced axial MRI scans in a 59-year-old woman with MMNST. A A 4.7 cm cystic mass at the para-aortic region, abutting onto the 3rd and 4th portion of the duodenum, showed a hyperintense solid part and a hypointense cystic part on T1WI, and B a hypointense solid part and a hyperintense cystic part on T2WI. C T2WI with fat suppression also showed a hypointense solid part and a hyperintense cystic part. D Contrast-enhanced T1WI showed identical enhancement with T1WI
bmcsurg.biomedcentral.com • CC-by-4.0
A para-aortic
malignant melanotic nerve sheath tumor mimicking a gastrointestinal stromal tumor: a rare case report and review of literature. A Coronal FIESTA (Fast Imaging Employing Steady-state Acquisition) sequence revealed a 4.7 cm cystic mass with a hyperintense solid part and a hypointense cystic part at para-aortic region, abutting onto the 3rd and 4th portion of the duodenum. B Coronal T2WI showed a hypointense solid part and a hyperintense cystic part
bmcsurg.biomedcentral.com • CC-by-4.0
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Melanotic schwannomas are an uncommon variant of schwannomas with malignant potential.

Epidemiology

The age groups of peak incidence are slightly younger than that of conventional schwannomas, occurring most often in the third through fifth decades .

Pathology

Melanotic schwannomas occur in two forms depending on the presence or absence of psammoma bodies:

  • non-psammomatous melanotic schwannoma
  • psammomatous melanotic schwannoma
    • Non-psammomatous melanotic schwannoma

    Non-psammomatous melanotic schwannomas almost invariably affect the spinal nerves and paraspinal sympathetic ganglia .

    Psammomatous melanotic schwannoma

    Psammomatous melanotic schwannoma also arise from spinal nerves and paraspinal ganglia, but may also involve cranial nerves and visceral autonomic nerves .

    Approximately half of individuals diagnosed with these tumors have underlying Carney complex .

    Macroscopic appearance

    Melanotic schwannomas appear as well circumscribed masses of variable pigmentation ranging from grey to black, depending on the amount of melanin .

    Microscopic appearance

    Melanotic schwannomas are composed of Schwann cells which contain melanosomes . Psammomatous tumors also contain psammoma bodies .

    Radiographic features

    MRI

    The appearances of melanotic schwannomas are similar to conventional schwannomas except that they usually have intrinsic high T1 signal and T2 signal loss due to the presence of melanin .

    Treatment and prognosis

    Complete resection is usually curative . Although generally indolent, approximately 10% of melanotic schwannomas are malignant . Metastatic disease occurs in a significant minority.

    Differential diagnosis

    Consider lesions with subacute hemorrhage, such as cavernous malformation, that can account for T1 hyperintensity .

    Siehe auch:
    Assoziationen und Differentialdiagnosen zu Melanotisches Schwannom:
    Schwannom
     
    www.eurorad.org • CC by-nc-sa-4.0
    maligner
    peripherer Nervenscheidentumor (MPNST)
    Wikipedia • CC BY-SA 3.0