A 70-year-old man with a recent diagnosis of adenocarcinoma of the lung presented with right hand clumsiness. Examination found a slight weakness of the right arm. A non-contrast cranial CT scan showed at least five hyperdense circular lesions with a diameter up to 2 cm, compatible with brain metastases (figure 1A).Twenty-two days earlier, a poorly differentiated adenocarcinoma of the lung had been diagnosed on biopsy of a mass in the left lower lobe of the lung. Staging at this time included a normal cerebral MRI (figure 1B). Positron emission tomography (PET) with fluorine 18-labeled fluorodeoxyglucose (F18-FDG PET) showed a tumour in the left lower lung and increased tracer uptake in isolated mediastinal lymph nodes but no additional lesions. Bone scintigraphy and abdominal sonography were normal. A contrast-enhanced thoracic CT scan hinted at a carcinomatous lymphangiosis of the contralateral lung. Advanced lung cancer was diagnosed and combined radiochemotherapy was initiated. 1 COMMENT The incidence of brain metastases is 10 times higher than that of primary malignant brain tumours. 2 Brain metastases indicate disseminated malignant disease and therapy is rarely curative. 3 The dynamics of cerebral metastases are variable, sometimes with extremely long latencies-up to 36 years-between cancer diagnosis and cerebral lesion in some types of tumour. 4 In lung cancer, Figure 1 A 70-year-old man with clumsiness of the right upper extremity. (A) Unenhanced axial CT scan shows at least five hyperdense circular lesions with a diameter up to 2 cm, compatible with brain metastases. (B) MRI brain scan (axial, T2-weighted) 22 days earlier in the same patient was adjudged unremarkable. At this time the patient was without neurological complaints and the examination was indicated in the staging process of lung cancer.