Solitary Fibrous Tumor of the Greater Omentum, Mimicking Gastrointestinal Stromal Tumor of the Small Intestine: A Case Report

Abstract

Solitary fibrous tumor (SFT) is one of the mesenchymal tumors, which rarely arises in the abdominal space. We report a very rare case of abdominal SFT, mimicking another mesenchymal tumor. A 52-year-old Japanese man was referred to our hospital for further evaluation and treatment of gallbladder polyp. Contrast-enhanced computed tomography (CT) showed an enhanced nodule within the gallbladder, and incidentally, also showed a well-circumscribed mass adjacent to the small intestine. The mass was depicted as slightly high density in plain CT, and with contrast-enhancement, the mass was partially stained in early phase and the stained area spread heterogeneously in delayed phase. Magnetic resonance imaging showed that the abdominal mass was depicted as slightly high intensity on T2-weighted imaging and low intensity on T1-weighted imaging. With double-balloon endoscopy and capsule endoscopy, we did not find any tumor inside the small intestine. These visual findings lead us to diagnose it as gastrointestinal stromal tumor of the small intestine with extraluminal growth. We planned to resect both the gallbladder polyp and the intraperitoneal tumor at the same time for pathologic diagnosis and treatment. When the operation was performed, we found a milk-white lobulated tumor on the greater omentum and the tumor was entirely resected. Microscopically, the gallbladder polyp was diagnosed as tubular adenoma, and the omental tumor was diagnosed as SFT. It is important to bear in mind that omental SFTs sometimes mimic other mesenchymal tumors and should be included in the differential diagnosis of abdominal tumor not revealed by endoscopy.

Endoscopic ultrasound FNA: An illustrated review of spindle cell neoplasms of the upper gastrointestinal tract including a novel case of gastric plexiform fibromyxoma

“…Ancillary immunohistochemical characterization of upper GI spindle cell proliferations may trigger definitive rather than descriptive diagnoses on small samples (Table ) and may allow for separation of GISTs, leiomyomata, schwannomas, carcinoid tumors, and PFs. It should also be noted that other spindle cell lesions, including but not necessarily limited to desmoid‐type fibromatoses, inflammatory fibroid polyps, and solitary fibrous tumors may enter the differential diagnosis . The upper GI tract is less frequently biopsied in comparison to other sites in larger EUS series; however, EUS with FNA and/or core biopsy is known to be an effective modality for the diagnosis of upper tract submucosal and spindle cell lesions .…”

“…They are usually detected incidentally, including but not necessarily limited to desmoid-type fibromatoses, inflammatory fibroid polyps, and solitary fibrous tumors may enter the differential diagnosis. [56][57][58][59][60][61][62] The upper GI tract is less frequently biopsied in comparison to other sites in larger EUS series; however, EUS with FNA and/or core biopsy is known to be an effective modality for the diagnosis of upper tract submucosal and spindle cell lesions. [63][64][65][66] Recent studies have suggested higher diagnostic accuracy with newer EUS coring needles, as well as the advantage of establishing diagnoses with fewer passes.…”

Malignant solitary fibrous tumor in retroperitoneum

“…However, the surgical and histologic results revealed a retroperitoneal SFT. Similarly, Urabe et al [17] reported a case of omental SFT that presented as a gastrointestinal stromal tumor of the small intestine. In their study, the CT scan revealed that the feeding artery to the tumor might be the left gastroepiploic artery, and it was finally proved that the tumor was originated from the greater omentum.…”

“…Recently, several studies have found that NAB2-STAT6 gene fusions occurred in the vast majority of SFTs. [15,16] In the study by Urabe et al, [17] they found that STAT6 was diffusely positive in a case of SFT. However, the role of IHC for STAT6 in SFTs remains uncertain.…”

Primary intrapulmonary solitary fibrous tumours

“…A solitary fibrous tumour (SFT) is a rare, slow-growing, mesenchymal neoplasm arising from the pleura, which is unrelated to asbestos exposure or cigarette smoking ( 1 ) and was initially described in 1931 ( 2 ). Over the past 80 years, SFTs have been identified in numerous extrapleural locations, including the nasal cavity ( 3 ), breast ( 4 ), stomach ( 5 ), bronchus ( 6 ), head and neck ( 7 ), liver ( 8 ), oesophagus ( 9 ), pelvic ( 10 ), pancreas ( 11 ), prostate ( 12 ), orbit ( 13 ), central nervous system ( 14 ), parotid gland ( 15 ), kidney ( 16 ), lung ( 17 ), sella turcica ( 18 ), heart ( 19 ), conus medullaris ( 20 ), omentum ( 21 ), infratemporal fossa ( 22 ), bladder ( 23 ), soft tissues of the extremities ( 24 ), palatine tonsil ( 25 ), diaphragm ( 26 ), mesentery ( 27 ), lumbar spine ( 28 ), thymus ( 29 ), oral cavity ( 30 ), spermatic cord ( 31 ), thyroid ( 32 ), rectum ( 33 ), salivary glands ( 34 ), retroperitoneum ( 35 ), larynx ( 36 ), trachea ( 37 ), adrenal gland ( 38 ), female genital tract ( 39 ), periosteum of bone ( 40 ), mediastinum ( 41 ) and hypopharynx ( 42 ).…”