Presentation
First seizure episode.
Patient Data
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 edema 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.
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 tumor 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 edema 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 ischemia, 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 tumor cells contain abundant eosinophilic cytoplasm, oval vesicular nuclei and prominent nucleoli. Frequent mitoses and areas of necrosis are present. Immunohistochemical results show tumor cells stain CK7+ and TTF1+; consistent with primary lung adenocarcinoma.
DIAGNOSIS: Brain, left temporal lesion: Metastatic moderately differentiated adenocarcinoma; consistent with lung primary.
Lobular mass in the upper zone of the right lung.
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 tumor traces in the surrounding white matter favor metastasis, which was confirmed histologically.
Further workup revealed a pulmonary mass, consistent with a primary tumor.