Brain metastasis: large cystic mass

Case contributed by Dr Bruno Di Muzio


First seizure episode.

Patient Data

Age: 62-year-old

CT Brain

Intra-axial mass lesion present within the posterior aspect of the left temporal lobe, predominantly hypoattenuating with peripheral rim enhancement, and a nodular region of enhancement along the lateral border measuring 9 mm. Diffuse white matter hypoattenuation surrounding the mass involving the left frontal, parietal and temporal lobes. There is resulting mass effect with asymmetry of the left lateral ventricle and left to right shift of midline structures measuring 6 mm.


MRI Brain

Complex mass in posterior aspect of the left temporal lobe is predominantly cystic and shows an excentric solid nodular component, which vividly enhances, shows restricted diffusion, and has elevated cerebral blood volume (CBV). No calcification was seen on the previous CT Brain. The fluid component of the tumour is homogenous and partially suppress on FLAIR, with a thin enhancing capsule. Spectroscopy traces at the margins of the lesion does not show choline peaks or reduced NAA. Vasogenic oedema surrounds the lesion and the mass effect also compress the left cerebral peduncle and left lateral ventricle, promoting a 6.6 mm rightward midline shift. Scattered foci of high T2/FLAIR signal abnormalities through the infra and supratentorial white matter are nonspecific, most likely representing chronic small vessel ischaemia, in a number distribution slightly over the expected for the patient's age group. Left pontine old lacunar infarct. There remain the brain is unremarkable. 

The patient was further screened for primary malignancy. The brain lesion was surgically approached: 

MICROSCOPIC DESCRIPTION: Sections of brain tissue show a moderately differentiated adenocarcinoma composed of glandular and papillary structures. Cohesive tumour cells contain abundant eosinophilic cytoplasm, oval vesicular nuclei and prominent nucleoli. Frequent mitoses and areas of necrosis are present. Immunohistochemical results show tumour cells stain CK7+ and TTF1+; consistent with primary lung adenocarcinoma.

DIAGNOSIS: Brain, left temporal lesion: Metastatic moderately differentiated adenocarcinoma; consistent with lung primary.


Chest Radiograph

Airspace opacity within the right upper lobe favours a pulmonary mass. 


CT Chest

Large right upper lobe mass and mediastinal lymphadenopathy suspicious for a primary lung cancer.

Case Discussion

This case illustrates the challenge in approaching a large brain cystic mass in the brain. Although both a cystic GBM and metastasis are possible diagnosis, subtle features such as the sparing of the cortex and absence of tumour traces in the surrounding white matter favours metastasis, which was confirmed histologically. 

Further workup revealed a pulmonary mass in keeping with the primary tumour. 

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Case information

rID: 47497
Case created: 18th Aug 2016
Last edited: 11th Sep 2016
Inclusion in quiz mode: Included

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