Brain metastasis (large cystic mass)

Case contributed by Dr Bruno Di Muzio

Presentation

First seizure episode.

Patient Data

Age: 60-65 years
CT

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 oedema surrounding the mass, with finger-like extensions, involving the left frontal, parietal and temporal lobes. There is a resultant mass effect with partial effacement of the left lateral ventricle and a left-to-right shift of midline structures measuring 6 mm.

MRI

MRI Brain

Complex mass in the posterior aspect of the left temporal lobe is predominantly cystic with an intensely enhancing eccentric solid nodular component, which shows restricted diffusion and an elevated cerebral blood volume (CBV). No calcification was seen on the previous CT brain. The fluid component of the tumour is homogeneous and partially suppressed on FLAIR, with a thin enhancing capsule. Spectroscopy traces at the margins of the lesion do not show a choline peak or reduced NAA. Vasogenic oedema surrounds the lesion and the mass effect also compresses the left cerebral peduncle and left lateral ventricle, resulting in 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, larger in number than expected for the patient's age group. Old pontine lacunar infarct left of midline.

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.

X-ray

Chest Radiograph

Lobular mass in the upper zone of the right lung.

CT

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 cystic mass in the brain. Although both a cystic GBM and metastasis are possible diagnoses, subtle features such as the sparing of the cortex and absence of tumour traces in the surrounding white matter favour metastasis, which was confirmed histologically. 

Further workup revealed a pulmonary mass, consistent with a primary tumour.

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Case information

rID: 47497
Case created: 18th Aug 2016
Last edited: 25th Jul 2017
Inclusion in quiz mode: Included

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