Multinucleated cells are frequently seen in association with a malignant neoplasm. Some of these multinucleated cells are considered to be neoplastic. The mechanism of neoplastic multinucleation remains unknown, but is considered to be induced by either cell-cell fusion or acytokinetic cell division. Myxofibrosarcoma consists of spindled and pleomorphic tumor cells and bizarre multinucleated giant cells. Some of these multinucleated cells are considered to be neoplastic. We studied the mitotic activity of the multinucleated cells by Ki-67 immunohistochemistry, and the dynamics and differentiation by live-cell video microscopy in the two myxofibrosarcoma cell lines to determine whether the mechanism of multinucleation is cell-cell fusion or acytokinetic cell division A Ki-67 immunohistochemical analysis revealed a high positive rate of multinucleated cells, as well as mononuclear cells, and mitotic ability was shown in the multinucleated cells. In live-cell video microscopy, most of the multinucleated cells were induced via the process of acytokinetic cell division. The current study indicates that a vulnerability of the cytoskeleton components, such as the contractile ring, causes multinucleation to occur from the telophase to the cytokinesis of the cell cycle.

Fine needle aspiration cytology (FNAC) and core needle biopsy (CNB) can provide tissue samples for the diagnoses of bone and soft tissue tumors. We evaluated the diagnostic accuracy of FNAC and CNB, the usefulness of the image-guided needle procedures, and assessed whether a discordance can influence the prognosis. We retrospectively examined the accuracy rates of FNAC and CNB procedures by analyzing results of 405 specimens of 389 patients. We evaluated the diagnostic accuracy of FNAC and CNB, compared the clinical effectiveness between the image-guided procedures and the blind procedures, and also compared survival rates between the true positive and the false negative cases for patients with high-grade malignant tumors. The accuracy rates of FNAC were 86.6% and 93.8% for CNB. In cases with non-palpable masses, there were significantly low sampling error rates in the image-guided procedure. There were no significant differences in progression-free-survival and overall survival rates in patients between the false negative and true positive cases. Both FNAC and CNB procedures had high accuracy rates. Limited to cases with no palpable masses, the image-guided procedure had a low sampling error rate and was an effective method for obtaining tissue samples.

A solitary fibrous tumour (SFT) is an unusual neoplasm typically found in soft tissues. Although SFTs can arise in the bones, they very rarely arise in the vertebral arch. Here, we describe a case of a SFT that arose in the vertebral arch of the first lumbar (L1) spinal vertebrae and mimicked osteosarcoma. A 49-year-old woman presented with a 2-month history of lower back pain and a lumbar region mass. Magnetic resonance imaging demonstrated a heterogeneously enhanced mass in the L1 vertebral arch. The patient received neoadjuvant chemotherapy, followed by a surgical procedure comprising an anterior spinal fusion and en bloc resection. Histologically, our initial diagnosis was osteosarcoma. The postoperative course was uneventful, and the patient received adjuvant chemotherapy. However, the tumour metastasised to the lung 5 years after the first surgery, and a second surgery was performed for lung tumour resection. The histology of the metastatic lung tumour appeared similar to that of the malignant SFT, and the specimen from the first surgery was re-examined. Immunohistochemically, the tumour was positive for STAT6. Reverse transcription-polymerase chain reaction revealed a NAB2-STAT6 fusion gene, thus confirming our final diagnosis of malignant SFT. The patient died of disease progression 8 years after the first surgery; however, there was no evidence of local recurrence. Malignant SFT in the vertebral arch is extremely rare and very difficult to distinguish histologically an osteoid from lace-like collagen. STAT6 immunostaining is useful for distinguishing malignant SFTs from other neoplasms. Although it is difficult to completely resect a SFT arising from the spine, we demonstrated the feasibility of an en bloc resection of spinal tumours arising from posterior elements, without local recurrence.