Gliosarcoma (GS) constitutes a minor fraction of primary glioblastoma (GBM), which is the most frequent malignant brain tumor in adults. Despite the fact that malignant gliomas are highly invasive, extracranial metastases are very rarely seen, and the mechanisms behind extracranial dissemination are still unclarified. We report a case of a 55-year-old male with a prior history of two distinct primary cancer types who, as a third independent type, developed GS with penetrating tumor growth to the skull and subcutaneous soft tissue via explosive spreading through a titanium net as well as extracranial metastases to the lumbar spine, paravertebral musculature, and most likely the right lung. The case illuminates the clinical challenge of diagnosing extracranial metastases from primary GBM and GS as these are still unexpected, especially in cases with possible competing diagnoses.