Malignant solitary fibrous tumor of urinary bladder: A rare clinical entity

Solitary Fibrous Tumors (SFTs) are mesenchymal tumors occurring in several sites. Urinary bladder SFTs are quite rare. Eighteen cases are described in the literature and only two of them had malignant features. SFTs comprise a histologic spectrum of mesenchymal neoplasms that show fibroblastic differentiation. The signs and symptoms are non specific. Immunohistochemistry plays a pivotal role in the diagnosis, differentiating SFTs from other spindle cell mesenchymal tumors. Malignant criteria are considered the large size, increased mitotic activity, focal necrosis or hemorrhage, nuclear atypia, hypercellularity and infiltrative margins. Clinical and biological behavior of bladder SFTs is usually not aggressive but cannot be safely predicted based on the pathologic features. Complete surgical resection is the cornerstone of treatment. We present the third bladder SFT case with malignant features and a mini literature review.