ABSTRACT
Solitary fibrous tumor (SFT) is an uncommon mesenchymal tumor and is classified as an Intermediate (rarely metastasizing) fibroblastic/myofibroblastic tumor (WHO 2013). It occurs as slow growing masses at any location in deep soft tissue, abdomen/pelvis, pleura, the extremities and other sites. We present a case of a 60-year-old woman with a slow growing swelling of the right thigh. On magnetic resonance imaging, a large lobulated, heterogeneously enhancing septated lesion was noted. Wide excision of the lesion showed a well-circumscribed tumor with gray white and mucoid areas. Light microscopic examination showed a circumscribed, partially encapsulated tumor composed of hypercellular areas with intervening hypocellular, hyalinized areas were seen and tumor cells showed diffuse strong CD34 positivity. Based on histopathology and immunohistochemistry (IHC), a final diagnosis of SFT was offered. SFTs belong to a spectrum of neoplasms from benign to malignant which can occur at myriad sites in the body. IHC forms the basis for confirmatory diagnosis. To prevent mislabeling as sarcoma, a high degree of suspicion and radio-histological correlation is warranted to arrive at a conclusive diagnosis.