Cerebral melanoma metastasis, meningiomas, and capillary teleangiectasia
Presentation
Cutaneous melanoma malignum, primary staging.
Patient Data
In the right parietal region close to the vertex a rounded, about 15 mm enhancing extra-axial mass is noted.
The lesion is more in line with meningioma than with melanoma metastasis, nonetheless further evaluation with MRI was recommended.
The rest of the study (not uploaded) demonstrated paratracheal lymphadenopathy, while the chest, abdomen and pelvis were unremarkable.
- The right parietal extra-axial mass shows vivid enhancement on MRI too, and only minimal peripheral SWI artifacts. Imaging appearance still favors meningioma over meningeal metastasis.
- A further, vividly enhancing similar extra-axial lesion can be detected in the right temporal region, adjacent to the petrous ridge.
- However, the most concerning finding is a small about 3 mm cortical-subcortical left parietal enhancing lesion, best seen on T1 C+, but inconspicuous on postcontrast FLAIR. On SWI the lesion demonstrates signal loss, likely representing hemorrhage. The lesion is in retrospect (note: potential hindsight bias) discernible on the postcontrast CT too.
- On the border of the right cerebral peduncle and brainstem an ill-defined about 6 mm focus of increased enhancement can be seen, showing SWI signal loss.
Case Discussion
The left parietal small lesion has the most profound clinical consequence despite being the smallest one. The location (bordering cortex and subcortical white matter), enhancement, and SWI signal loss are characteristic for intracranial melanoma metastases.
The right parietal and temporal extra-axial lesions are more in line with meningiomas. Nonetheless their presence lead to the prompt further imaging with MRI, and thus serendipitous discovery of the actual metastatic lesion.
The nature of the cerebral peduncle-brainstem lesion is equivocal, although the mottled enhancement, location and SWI signal loss are highly suggestive of a CNS capillary teleangiectasia rather than a mass lesion.