Aim: Immunohistochemistry findings along with clinical features, are significantly important in differentiating the Extrapleural SFT in the neck, from other well-circumscribed mesenchymal neoplasms at this locations. Introduction: We present a rare case of a Extrapleural SFT in a 57 years old man in the neck, without significant past medical history. Material and Methods: The patient had a painless slow growing tumor, in right sight of the neck, diagnosed with physical examination. Total excision with local anesthesia was done, without previously biopsy of the tumor and other clinical investigations. Standard procedures for histology and immunohistochemical stains were done. Results: Tumor was well circumscribed, encapsulated measuring 5,5x4x4 cm. On section, the cut surface had a multinodular, whitish and firm appearance. On microscopic examination tumor was composed of alternating hypocellular and hypercellular areas separated from each other by thick bands of collagen and branching haemangiopericitoma like vessels. The tumor cells were round to spindle-shaped with little cytoplasm, indistinct borders, dispersed chromatin within vesicular nuclei. Area of myxoid change and subcapsular focus of hemorrhage was present, and 2 mitoses/10 HPF were found. Immunohistochemistry revealed diffuse positivity for CD34, Vimentin and BCL2, focal positivity for CD99, S100, SMA, and negativity for CKWS and EMA. Ki67 showed low proliferating index 3-5%. Conclusion: Although most cases of SFT are benign, there is no strict correlation between morphology and behavior, so patients with extrapleural solitary fibrous tumor have need of long-term post-resection follow-up. Further studies are needed to determine the optimal management of these neoplasms.

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