We present a unique case of a patient simultaneously diagnosed with solitary fibrous tumor (SFT) and unrelated adenocarcinoma of the lung, both proven with separate pathology. It was subsequently found that the SFT had metastasized to the brain by additional pathology, and not the predicted adenocarcinoma. SFTs are a rare mesenchymal neoplasm that accounts for less than 2% of all reported soft tissue tumors. SFTs most commonly arise in the thoracic cavity, but are frequently found in various locations throughout the body, and rarely metastasize to the brain. This case highlights that rare neoplasms, such as SFT, should not be ruled out as a potential cause of metastasis. Due to the rarity of this clinical situation, we also provide a review and discussion of previously reported SFT cases and the use of postoperative radiation therapy. The optimal treatment for individual patients remains unclear in this unique situation. Surgical resection followed by adjuvant Gamma Knife radiation therapy to the surgical bed appears to be a safe option for local treatment of SFT in select patients. Further studies are needed of this rare clinical situation in order to better understand and optimize future treatments for patients with SFT and metastasis to the brain.