Intracranial metastatic melanoma
Updates to Article Attributes
Intracranial metastatic melanoma is the third most common brain metastasis.
For a broad discussion about the primary tumour or brain metastasis in general, please refer on the articles:
Epidemiology
A population-based study of 169,444 cancer patients from 1973 to 2001 in Detroit revealed that ~7% of patients diagnosed with melanoma subsequently developed intracranial metastasis 2.
Clinical presentantion
These patients can commonly present with headaches, seizures, mental status alterations, ataxia, nausea and vomiting, and visual disturbances. However, 10% of patients may be asymptomatic.
Pathology
Melanoma metastases can be artificially 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 metastases 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 melanoma metastases examined 7.
Radiographic features
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.
CT
Typically, intracranial melanoma metastases consist of a single or multiple 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), and 72% of these lesions had increased attenuation 3. Cystic degeneration and necrosis are rarely seen in these tumours 3,4.
- NECT: single to multiple nodules of increased attenuation localized to the gray/white matter junction; variable oedema and frequent intratumoural hemorrhage present
- CECT: nodules typically enhance; dural-based, well enhanced lesions are impossible to differentiate from meningiomas
MRI
The blood products alter the signal on MRI resulting in hyperintensity on T1 and hypointensity on T2 images. However, it should be noted that the melanin pigment have parallel effects on T1 and T2 relaxation times 6. Thus, the signal changes seen on MRI may be due to either melanin or blood products.
- T1: typically hyperintense secondary to hemorrhage or melanin (as above)
- T2: typically hypointense
-
T1 C+
(Gd): typically enhances in a peripheral rim pattern or a diffusely heterogeneous pattern
Treatment and 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.
Differential diagnosis
- other haemorrhagic intracranial metastases:
- other melanotic tumours
-
other haemorrhages
-
haemorrhage into primary
haemorrhagicbraintumours- tumour (e.g. glioblastoma
- primary lobar haemorrhage
-
haemorrhage into primary
Related articles
-<strong>T1 C+ (Gd):</strong> typically enhances in a peripheral rim pattern or a diffusely heterogeneous pattern</li>- +<strong>T1 C+:</strong> typically enhances in a peripheral rim pattern or a diffusely heterogeneous pattern</li>
-<li>primary haemorrhagic brain tumours<ul><li><a href="/articles/glioblastoma">glioblastoma</a></li></ul>- +<li>other melanotic tumours<ul>
- +<li><a href="/articles/meningeal-melanocytoma">meningeal melanocytoma</a></li>
- +<li><a href="/articles/melanotic-meningioma">melanotic meningioma</a></li>
- +</ul>
- +<li>other haemorrhages<ul>
- +<li>haemorrhage into primary brain tumour (e.g. <a href="/articles/glioblastoma">glioblastoma</a>)</li>
- +</ul>
- +</li>