Cutaneous metastasis from an intracranial glioblastoma multiforme

A 34-year-old white man with a history of an intracranial glioblastoma multiforme was treated with surgical excision and radiotherapy. Five months later, the patient had a rapidly growing scalp mass develop. This lesion was excised, and the histology revealed a tumor that was similar to the originally resected intracranial glioblastoma. Immunohistochemistry for general neuroepithelial derivation (S-100 protein) and for glial fibrillary acidic protein (GFAP) was positive, whereas mesenchymal, epithelial, and neuronal markers were negative. This immunohistochemistry pattern was identical to the original tumor. Although metastasis of this tumor is not uncommon, metastasis to the skin has never been reported. To our knowledge, this is the first reported case of cutaneous metastasis from glioblastoma in the world literature.