Malignant Solitary Fibrous Tumor of Tandem Lesions in the Skull and Spine
A 54-year-old female patient was referred to our spine center with a two-month history of lower back pain and radiating pain in both legs, which was persistent even at night. She had constipation with a symmetric leg muscle power grade of IV/V. Lumbo-sacral magnetic resonance imaging (MRI) showed a heterogeneously enhanced 6.7 cm sized lesion involving the sacrum, sacroiliac joint, and both illium with extraosseous mass formation containing a necrotic portion ().\nWe performed positron emission tomography/computed tomography (PET/CT) and bone scan to assess for metastatic lesion. PET/CT and bone scan revealed hot uptake in the sacro-pelvic area, T8, and occipital skull area. Thoracic MRI showed an epidural enhancing 1.7 cm sized lesion in the posterior element of T8 (). In addition, findings on brain imaging studies showed an enhancing mass measuring 3.8 cm with occipital bone destruction and mild brain compression (). Percutaneous biopsy of S1 was performed for diagnosis. Pathology of the biopsy indicated a type undetermined malignant neoplasm, suspected as a malignant spindle cell tumor.\nOn angiography, large feeding vessels were observed in sacral lesion, and tumor embolization using Gelfoam was performed prior to perform an open surgery. Partial removal of the tumor in sacroiliac area was done; then, gross total removal of the tumor at T8 was subsequently performed in a single stage. The tumor was extremely hypervascular and was not well demarcated. For the remnant tumor of the sacroiliac area, postoperative stereotactic radiosurgery using Novalis Tx (BrainLAB, Inc., Ammerthalstrabe, Germany) was administered at a dose of 4 fractionated 32 Gy, which encompassed 100% of the tumor volume. After open surgery and radiosurgery, her lower back pain and radiating pain showed improvement. Three weeks after first open surgery, gross total removal of the tumor in the occipital skull was performed after tumor embolization.\nTumors of the sacro-pelvic area, T8, and occipital area showed identical histologic features. The tumors consisted of fusiform or spindle cells and showed a hemangiopericytoma-like perivascular pattern or a so-called patternless pattern, with intervening irregular hyalinzed collagen bundles, typical for a solitary fibrous tumor. The tumors showed multifocal necrosis, high cellularity, and marked cellular atypia. Mitotic figures were frequently observed [up to 10/10 high-power fields (HPFs)]. By immunohistochemistry, the tumor cells were positive for CD34, CD99, Bcl-2 and EMA (focal-like +). As a result, the tumors were diagnosed as malignant solitary fibrous tumor ().\nAlthough there was a lack of clinical evidence about adjuvant chemotherapy or radiotherapy, adjuvant chemotherapy with adriamycin and cisplatin was administered. However, just 2 days after starting adjuvant chemotherapy, one month after the initial surgery, she complained of aggravated upper back pain and paraparesis. Findings on follow-up thoracic MRI showed a recurred expansive posterior epidural mass with cord compression at T8 (). For the recurred tumor at T8, stereotactic radiosurgery was administered at a dose of 4 fractionated 32 Gy. After radiosurgery, her upper back pain and paraparesis showed improvement.\nGradually, she complained of progressive whole body pain. Despite chemotherapy, follow-up whole spine MRI and chest radiography revealed metastasis in multiple vertebrae and both lungs. Although palliative cervical and thoracic spine radiotherapy (dose of 5 fractionated 15 Gy) was performed for relieving intractable pain, her symptoms did not show improvement and the patient finally died due to poor general condition six months after first open surgery.