Presentation
Difficulty with speech.
Patient Data
In the left frontal operculum, near Broca's area, is a vividly enhancing centrally non-enhancing (presumably necrotic) mass. It is surrounded by a large amount of vasogenic edema that spares the overlying cortex and basal ganglia. It results in subfalcine herniation and rightward midline shift.
It is an isolated abnormality.
A peripherally enhancing mass is centered on the left frontal operculum. It is surrounded by abundant surrounding vasogenic edema, which spares the overlying cortex and extends into the external and extreme capsule and anterior limb of the internal capsule sparing the deep grey matter of the basal ganglia.
Laterally, it has a solid component with elevated cerebral blood volume. This component also has high DWI signal and low ADC values (~650 x 10-6 mm2/s) implying high cellularity, whereas the edematous white matter has uniformly facilitated diffusion.
Within the necrotic component, small areas of signal loss on SWI are consistent with blood products.
MR spectroscopy over the lesion demonstrates a high choline peak and high lactate peak. In the adjacent edematous white matter, the spectroscopy trace is essentially normal.
A second small rounded solid enhancing nodule is seen at the grey-white matter junction of the frontal pole.
Conclusion:
Two lesions in the frontal lobe either represent cerebral metastases or, less likely, a high-grade multifocal glioma (e.g. glioblastoma or grade 4 diffuse astrocytoma). The absence of any non-enhancing tumor and the normal spectroscopy of surrounding edematous brain, as well as the location near the grey white matter border and vast quantities of vasogenic edema strongly favor metastases.
Case Discussion
On further imaging, a lung mass (not shown) was identified, and it was biopsied.
Histology
Anthracotic, fibrotic and chronically inflamed fibrous tissue with a malignant infiltrate composed of solid sheets and small solid nests. The malignant cells are polyhedral with large irregular nuclei, prominent nucleoli and variable amounts of pale cytoplasm. The malignant cells are AE1/3, CAM5.2, CK7, TTF1 and NapsinA positive. P40, CK20, CDX2, PSA and SOX10 are negative.
Final diagnosis: adenocarcinoma with primary lung immunophenotype.
Discussion
Although a number of imaging features favored cerebral metastasis over a multifocal high-grade glioma, in most instances, a history of malignancy or evidence of previously not-diagnosed tumor elsewhere can be found in patients with metastases.
Occasionally, a patient has a history of malignancy but has a concurrent unrelated glioblastoma; they are, after all, fairly common tumors in the elderly.
Relatively uncommonly, a patient with a cerebral metastasis will present with no prior history of malignancy and no evidence of a primary lesion on CT and CT PET, referred to as brain metastases of cancer of unknown primary 1,2.
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