Intracranial metastatic melanoma

Changed by Ayush Goel, 9 Nov 2014
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Melanoma is the third most common primary neoplasm that metastasizes to the brain1.  A population-based study of 169,444 cancer patients from 1973 to 2001 in Detroit revealed that 6.9% of patients diagnosed with melanoma subsequently developed intracranial metastasis 2.

Pathology

Melonoma metastases can be artifically divided into "melanotic" (containing greater than 10% melanotic cells on histopathology) or "amelanotic" (containing less than 10% melanotic cells).  In 1995, Isiklar et al. published a study in the AJR where only melanotic metastastes provided consistent and reliable MR findings (hyperintense on T1 and hypointense on T2).  The MR findings of amelanotic metastases were non-specific.  Unfortunately, melanotic metastases made up only 25% of the total cerebral melonoma metastases examined 7.

Radiographic features

CT

Typically, intracranial melanoma metastases consist of a single or multiple radiodense nodules with increased attenuation on CT.  Out of a series of 101 patients with cerebral melanoma metastases, 62% were found to have multiple lesions (53% localized bilaterally).  72% of these lesions had increased attenuation 3. Cystic degeneration and necrosis are rarely seen in these tumours 3,4.

  • NECT: - single single to multiple nodules of increased attenuation localized to the gray/white matter junction ; variable edema and frequent intratumoural hemorrhage present. 
  • CECT:- nodules nodules typically enhance; dural-based, well enhanced lesions are impossible to differentiate from meningiomas.
MRI

Intratumoural haemorrhage is a much more common feature of melanoma metastases in comparison to other brain metastases 5. Other than choriocarcinoma, metastatic melanomas are the most frequent metastases that are complicated by massive haemorrhage 6. The blood products alter the signal on MR, resulting in hyperintensity on T1 and hypointensity on T2 images.  However, it should be noted that the indole semiquinones and semiquinones of melanin pigment have parallel effects on T1 and T2 relaxation times 6. Thus, the signal changes seen on MR may be due to either melanin or blood products.

  • T1:- typically typically hyperintense secondary to hemorrhage or melanin (as above)
  • T2: - typically typically hypointense
  • T1 C+ (Gd):- typically typically enhances in a peripheral rim pattern or a diffusely heterogeneous pattern.

Prognosis

The prognosis of cerebral metastatic melanoma is dismal. Without treatment, the average survival time from the beginning of neurologic symptoms was 65 days in one study 8-9. Even with chemotherapy and radiotherapy, the survival time has only been extended to a range of 4 months to approximately 2 years 10.

Related articles

See also

  • -<strong>NECT</strong> - single to multiple nodules of increased attenuation localized to the gray/white matter junction ; variable edema and frequent intratumoural hemorrhage present. </li>
  • +<strong>NECT:</strong> single to multiple nodules of increased attenuation localized to the gray/white matter junction ; variable edema and frequent intratumoural hemorrhage present. </li>
  • -<strong>CECT </strong>- nodules typically enhance; dural-based, well enhanced lesions are impossible to differentiate from meningiomas.</li>
  • +<strong>CECT:</strong> nodules typically enhance; dural-based, well enhanced lesions are impossible to differentiate from meningiomas.</li>
  • -<strong>T1 </strong>- typically hyperintense secondary to hemorrhage or melanin (as above)</li>
  • +<strong>T1:</strong> typically hyperintense secondary to hemorrhage or melanin (as above)</li>
  • -<strong>T2</strong> - typically hypointense</li>
  • +<strong>T2:</strong> typically hypointense</li>
  • -<strong>T1 C+ (Gd) </strong>- typically enhances in a peripheral rim pattern or a diffusely heterogeneous pattern.</li>
  • +<strong>T1 C+ (Gd):</strong> typically enhances in a peripheral rim pattern or a diffusely heterogeneous pattern.</li>
Images Changes:

Image 8 CT (non-contrast) ( create )

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