[An autopsy case of miliary brain metastases]

A 57-year-old man was admitted to our hospital with a diagnosis of psychiatric emergency. His symptoms were similar to encephalitis, metabolic encephalopathy or acute depressive psychosis because of poor focal neurological signs. Laboratory examinations, including routine hematological and biochemical investigations, serum vitamin B1 B12 levels, and cerebrospinal fluid obtained by lumbar puncture, were normal. Brain CT was also normal, therefore it was difficult to make a diagnosis. But, we could clinically diagnose him as having pulmonary adenocarcinoma with numerous metastatic nodules of the brain. Because miliary lesions in the cerebral hemispheres, brainstem and cerebellum were disclosed on brain MRI. Furthermore, chest CT revealed the lung tumor in the left S8 area. In addition, laboratory examination showed a rise of tumor marker and cytologic examination of sputum revealed class V. Fluid-attenuated inversion recovery and contrast-enhanced MR images demonstrated more prominently miliary metastases, in particular lesions in the cerebral cortex, than T1- and T2-weighted images. There was neither edema in the surrounding region of metastatic nodules nor mass effect on all MR images. Spinal MRI showed no metastatic lesions. The patient died of respiratory failure at the age of 58, about eight months after the disease onset. The brain weighed 1,575 g. Neuropathological findings revealed diffuse miliary brain metastases located in all parts of the brain, except for the medulla oblongata. Histological examination disclosed multiple metastases from a well-differentiated adenocarcinoma with a predominant tubular pattern. There was neither edema nor glial reaction in the surrounding area of metastatic lesions. Many pseudorosettes were recognized and carcinoma cells, extending through perivascular spaces into the subarachnoid space, were noticed.