Massive malignant solitary fibrous tumor arising from the bladder serosa: a case report

Abstract

IntroductionSolitary fibrous tumors are rare neoplasms of mesenchymal origin. They are often of low malignant potential and rarely metastasize. While they frequently arise from the pleura, they can occur at any soft tissue site in the body. We present a case of a large (28 × 21cm) malignant solitary fibrous tumor arising from the bladder serosa. In addition, the clinicopathologic features, differential diagnosis, cytogenetics and management of this rare disease are discussed, along with a review of the existing literature on this topic.Case presentationAn otherwise healthy 41-year-old Caucasian man presented with weight loss and progressive abdominal bloating. A subsequent computed tomography scan of his chest, abdomen and pelvis revealed a 26.8 × 21cm intra-abdominal mass occupying most of his abdominal cavity. The inferior vena cava was compressed, and the mass extended inferiorly to his upper pelvis abutting the superior dome of his bladder. He underwent operative resection and the resected mass measured 28 × 21 × 18cm and weighed 4.8kg. The cut surface revealed a gray-white mass with an ill-defined whorled-like pattern, with randomly assorted tan fleshy nodules. A histologic evaluation revealed variable, alternating hypercellular and hypocellular areas, with areas of necrosis. The tumor cells varied from spindle to epithelioid within a hyalinized stroma. In the hypercellular areas, the tumor cells showed moderate atypia with high mitotic activity. The histological features combined with immunophenotyping were suggestive of a malignant solitary fibrous tumor that grossly appeared to be growing from the bladder serosa, specifically the intraperitoneal superior dome of the bladder. Our patient is currently eight months post-surgery without evidence of recurrence.ConclusionsExtrapleural occurrences of solitary fibrosis tumors are being increasingly observed. Malignant solitary fibrosis tumors of the urinary bladder, however, are very rare. As there are no pathognomonic features of malignancy, surgical resection is often both diagnostic and therapeutic, as was the case in our report.

A small solitary fibrous tumor of the bladder

“…[12][13][14][15][16] Sometimes, a diagnosis of malignant soft tissue tumor was considered. Actual malignant bladder SFT has been described, [7] while to the best of our knowledge, this is the first case of a SFT of just 4 mm.…”

Solitary fibrous tumour of the genitourinary tract: a clinicopathological study of 11 cases and their association with theNAB2-STAT6fusion gene

“…The third case in this study (case 9) showed a rapid recurrence after 12 months. This behaviour may relate to proposed mechanistic pathways for development of a malignant solitary fibrous tumour involving dedifferentiation of a pre-existing benign tumour and acquisition of additional complex genetic aberrations 32 33. As in other sites, studies are currently expanding the understanding of other genes overexpressed in solitary fibrous tumours, which may lead to insight into the mechanisms of progression and insight into subsequent therapeutic targets 9 32–34…”

Solitary fibrous tumor of the seminal vesicle

“…[1] SFT can be found in many parts of the body and generally appears in the visceral pleura. Additionally, SFT is also observed in the head and neck region, [2] bones, [3,4] breasts, [5] the abdominal pelvic cavity, [6] and retroperitoneum. However, SFT arising from the seminal vesicle is exceedingly rare.…”