Glioblastoma NOS (mimicking a melanoma metastasis)

Case contributed by Dr Bruno Di Muzio

Presentation

Clinically weak in left upper limb, less so in left lower limb. Previous history of melanoma excision on the right foot.

Patient Data

Age: 80 years
Gender: Male

 

In the right parietal lobe is an ill-defined 24 x 16 x 17 mm mixed attenuation lesion, which has a low attenuation center and a high attenuation rim, which appears thick walled. There is extensive surrounding edema with some minor mass effect on the right lateral ventricle as well as some associated gyral edema.

Elsewhere, there is involutional change in keeping with the patient's age of 81 years. No further localized grey or white matter lesion is seen. No surgically drainable collection.

Bones, air sinuses and orbits appear normal. No fracture of cranial base or vault. No scalp hematoma.

CONCLUSION:

Right parietal lesion is suspicious for a metastasis, including a hemorrhagic/radiodense metastasis such as a melanoma. Post contrast examination +/- MRI would provide more information.

Centered at the grey-white matter junction of the right precentral gyrus is a peripherally enhancing lesion which demonstrates foci of susceptibility artefact on EPI, increased CBV and increased restricted diffusion peripherally. The lesion is surrounded by a large amount of white matter T2/FLAIR hyperintensity, that does not involve the overlying cortex. Mass effect is characterized by local cortical sulcal effacement and mild compression of the right lateral ventricle. No midline shift. Spectroscopy demonstrates a lactate peak.

The remainder of the brain is unremarkable.

Conclusion:

Right posterior frontal lesion is favored to represent a metastasis. Foci of susceptibility artefact are in keeping with a hemorrhagic metastasis such as that which can be seen with melanoma.

Case Discussion

This case demonstrates typical features of a metastatic lesion: 

  • elderly patient with a previous cancer history (cutaneous melanoma)
  • cortico-subcortical solitary nodule
  • peritumoral edema out of proportion with the tumor size
  • hyperdense/hemorrhagic component (fits with melanoma metastases) 

However, a stereotaxic biopsy confirmed this to be a glioblastoma. It is relevant to keep in mind that for this case GBM is the most likely differential diagnosis.   

Note: IDH mutation status is not provided in this case and according to the current (2016) WHO classification of CNS tumors, this tumor would, therefore, be designated as a glioblastoma NOS

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Case information

rID: 38258
Published: 15th Jul 2015
Last edited: 14th Aug 2019
Tag: rmh
Inclusion in quiz mode: Included

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