Brain metastasis from an unknown primary, or primary brain tumour? A diagnostic dilemma

Abstract

Brain metastasis is increasingly common, affecting 20%-40% of cancer patients. After diagnosis, survival is usually limited to months in these patients. Treatment for brain metastasis includes whole-brain radiation therapy, surgical resection, or both. These treatments aim to slow progression of disease and to improve or maintain neurologic function and quality of life.Although less common, primary brain tumours produce symptoms that are similar to those of brain metastasis. Glioblastoma, the most common malignant tumour of the brain, has a median survival of less than 12 months. Patients are often treated with surgical resection followed by radical radiation therapy and chemotherapy.Here, we present 2 separate cases of lesions in the brain radiologically compatible with brain metastasis. In both cases, no primary cancer site had been established, and neurosurgical intervention was sought to obtain a pathologic diagnosis. Both cases were pathologically confirmed as glioblastoma. These cases demonstrate the importance of differentiation between brain metastases and primary brain tumours to ensure that the appropriate management strategy is implemented.

Keywords: Brain metastasis; glioblastoma multiforme; unknown primary; wbrt; whole-brain radiation therapy.

FIGURE 1

Post-contrast computed tomography (A) before resection demonstrates a part-solid, part-cystic, ring-enhancing lesion in the left temporal lobe; (B) immediately following resection demonstrates a resection cavity containing air and fluid without an enhancing abnormality (left frontal postsurgical pneumocephalus); (C) 2 months post-resection demonstrates expansion of ring enhancement within the left temporal lobe, associated with increased perilesion edema and mass effect.

FIGURE 2

Pathology slide of glioblastoma multiforme (case 1). A section stained with hematoxylin and eosin shows frank atypia in this astrocytic tumour. Brisk mitotic activity is noted (arrows).

FIGURE 3

Volumetric (A) post-gadolinium T1 and (B) flair (fluid-attenuated inversion recovery) sequences 3 weeks post-resection, demonstrating a left temporal craniotomy, with a combination of underlying postsurgical changes and residual enhancing lesion surrounded by infiltrative edema.

FIGURE 4

Pathology slide of glioblastoma multiforme (case 2). Some of the classic features of anaplastic astrocytoma are illustrated: nuclear pleomorphism, palisading necrosis (P) and brisk mitotic activity (arrows).

FIGURE 5

Magnetic resonance imaging slices showing glioblastoma multiforme (case 2). (A–C) Axial T1 post-gadolinium images and (D–F) corresponding axial flair (fluid-attenuated inversion recovery) slices at the same levels. Ring-enhancing masses can be seen in (A) the right temporal lobe, (A) right occipital lobe, (B) right inferior parietal lobe, (C) right frontal lobe, and (C) right superior parietal lobe. Under flair, hyperintensity can be seen around each lesion (D–F). Additional flair hyperintensity is seen intervening between the right frontal lobe and the right superior parietal lobe lesions (F).