A case of metastatic brain tumor mimicking an expanding thalamic hematoma.

BACKGROUND: Brain tumor are a major etiology of secondary intracranial hemorrhage (ICH) because ICH in patients with cancer often occurs from an intratumoral hemorrhage. However, it is sometimes difficult to detect a tumor when it is tiny and buried, especially during initial examination. CASE DESCRIPTION: A 65-year-old woman who was diagnosed with pulmonary small cell carcinoma 6 months previously developed sudden-onset consciousness disturbance and left hemiparesis. Head computed tomography (CT) showed a round, high-density lesion with a diameter of 31 mm in the right thalamus. There was no enhancement with administration of contrast agent. Five days later, CT revealed significant progression of the hematoma in the thalamus with perifocal edema. She underwent total removal of the hematoma. Histopathological examination revealed a tiny cluster of metastatic cancer tissue within the hematoma. CONCLUSIONS: When cerebral hemorrhage occurs in a cancer patient, we must consider the possibility of hemorrhage due to a brain metastasis.