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Cerebral metastasis mimicking glioblastoma

Case contributed by Frank Gaillard
Diagnosis certain

Presentation

Headache. Cerebral mass and pulmonary mass on CT.

Patient Data

Age: 55 years
Gender: Female

A large heterogeneously enhancing mass replaces almost the entirety of the left temporal lobe, with evidence of prominent subependymal/ependymal spread along the trigone of the lateral ventricle. It demonstrates small areas of signal loss consistent with a blood product but no evidence of calcification. Markedly elevated cerebral blood volume is noted in the solid non-necrotic components. MR spectroscopy demonstrates elevation of choline, with prominent lipid and lactate components in the necrotic areas. Diffusion weighted imaging is unusual, with prominent diffusion restriction of the nonenhancing component (ADC values as low as 500 x 10^-6 mm^2/s) presumably representing thick necrotic material probably with blood products.

The mass exerts significant local mass effect with 5 mm of midline shift and left uncal herniation and distortion of the left cerebral peduncle. Scattered throughout the intracranial cavity are multiple other tiny punctate regions of contrast enhancement, most of them clearly leptomeningeal.

Conclusion: Despite the unusual appearance and subependymal spread, given the presence of pulmonary masses and leptomeningeal nodules, this large mass presumably represents a metastasis. If there were no systemic malignancy then a high-grade primary tumor with CSF seeding would be a differential.

Spiculated nodule within the lingula segment of the left upper lobe. Separate enlarged left hilar lymph nodes resulting in high-grade pulmonary artery stenosis, likely to a point of focal occlusion of central left lower lobe pulmonary arterial branches. Left hilar nodal disease results in moderate extrinsic narrowing of the central left lower lobe airways. The subcarinal node is mildly prominent measuring 13 mm in short axis.

A linear structure running through the left mediastinum, although non-contrast filled (right upper limb contrast injection) appears to represent a left-sided SVC arising from the left brachiocephalic vein, draining into the coronary sinus.

Within the left lower lobe, there is an ill-defined 10 mm pulmonary nodule. Within the right middle lobe, a small triangular nodule arising from the undersurface of the horizontal fissure is typical for a small peri-fissural nodule. No pleural effusions. No pericardial effusion.

Conclusion: Spiculated solid lingula pulmonary nodule is concerning for primary lung cancer with associated left hilar nodal metastases. 

Case Discussion

The patient went on to have a resection. 

Histology: 

Sections show brain tissue infiltrated by invasive adenocarcinoma. The tumor forms an extensive network of broad, branching and anastomosing papillary structures and irregularly-shaped acini. The papillae and acini are lined by malignant cells that are markedly enlarged and pleomorphic, with irregularly-shaped nuclei, vesicular chromatin, prominent nucleoli and large amounts of eosinophilic cytoplasm. There is copious necrotic debris.

IMMUNOHISTOCHEMISTRY:

The malignant cells are diffusely and strongly positive for CK7 and TTF1.

They are negative for CK20, CDX2, ER, PR, Gata3 and Pax8.

FINAL DIAGNOSIS: Metastatic adenocarcinoma consistent with lung origin.

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