Giant cells in cortical tubers in tuberous sclerosis showing synaptophysin-immunoreactive halos

We describe a characteristic pattern of immunoreactivity for synaptophysin in tuberous sclerosis. We analyzed cortical tubers from surgical specimens taken from six patients with tuberous sclerosis, which were obtained by surgical resections for the treatment of intractable seizures. The cortical tubers were characterized by blurred lamination of the cerebral cortex, hypercellularity, and gliotic changes. Neuropil in the cortex of cortical tubers showed reduced immunoreactivity for synaptophysin in all patients. 'Giant cells' were investigated in the cortex and white matter regions of cortical tubers. Some 'giant cells' had neuronal characteristics such as Nissl substance, a centrally placed chromatin-marginated nucleus, prominent nucleolus, positive immunoreactivity for microtubule-associated protein 2, and negative immunoreactivity for glial fibrillary acidic protein. Other 'giant cells' were indeterminate in cell type because they lacked Nissl bodies, distinct nucleolus, consistent immunoreactivity for microtubule-associated protein 2 and glial fibrillary acidic protein. Almost all 'neuronal giant cells' and some of the 'indeterminate giant cells' in the white matter showed intense immunoreactivity for synaptophysin: cell borders were surrounded by an intense immunoreactive halo. In conclusion, these immunohistochemical patterns for synaptophysin assist in characterizing these abnormal cells in the cortical tubers of patients with tuberous sclerosis.