Occult malignant astrocytoma of pons with extracranial metastasis to bone prior to craniotomy

A 23-year-old man presented with signs of increased intracranial pressure. CAT scan, cisternogram, and angiogram on admission were reported to be normal. Lumbar puncture revealed elevated pressure and protein of 500 mg-%. CSF cytology revealed malignant tumor cells. A brain biopsy and decompression were carried out to reveal diffuse subarachnoid invasion by malignant tumor cells. Immunohistochemical studies using anti-glial fibrillary acidic protein serum revealed tumor cells to be positive for GFA protein. A lumbosacral CAT scan 9 days after surgery revealed numerous sclerotic densities involving bony pelvis, sacrum, T-12 vertebra and left femoral head. No definite primary site of tumor was found antemortem in the brain or any other organ. Autopsy demonstrated diffuse subarachnoid spread of malignant tumor in brain and spinal cord. Malignant astrocytoma was found in the midline pons projecting into the 4th ventricle. The histology of the neoplasm was identical in all sites including bone. No other tumor was found at autopsy. The vascular invasion by the tumor cells in the pons and distant bony metastasis in this case suggest hematogenous spread. A review of the lumbar X-ray taken 6 weeks prior to admission and the presence of well-established bony lesions within 10 days of craniotomy suggest that this is a rare case of extraneural metastasis of glioma occurring prior to surgery. The midline location of clinically occult pontine glioma and the presence of bony metastasis created difficulty in the diagnosis but immunohistochemical studies proved to be crucial in establishing correct diagnosis antemortem.