Solitary Fibrous Tumor of the Stomach

Mesenchymal tumours of the gastrointestinal tract

Mesenchymal tumours represent a heterogenous group of neoplasms encopassing benign, intermediate malignancy, and malignant entities. Sarcomas account for approximately 1% of human malignancies. In consideration of their rarity as well as of intrinsic complexity, diagnostic accuracy represents a major challenge. Traditionally, mesenchymal tumours are regarded as lesions the occurrence of which is mostly limited to somatic soft tissues. However, the occurrence of soft tissue tumours at visceral sites represent a well recognized event, and the GI-tract ranks among the most frequently involved visceral location. There exist entities such as gastrointestinal stromal tumours (GIST) and malignant gastointestinal neuroectodermal tumors that exhibit exquisite tropism for the GI-tract. This review will focus also on other relevant clinico-pathologic entities in which occurrence at visceral location is not at all negligible.

Gastric Inflammatory Fibroid Polyp: A Rare Cause of Occult Upper Gastrointestinal Bleeding

Inflammatory fibroid polyps (IFPs) are rare mesenchymal lesions that can arise throughout the gastrointestinal tract. These tumors represent less than 0.1% of all gastric polypoid lesions and are frequently found incidentally on endoscopic evaluation. While presenting symptoms depend on the location of the tumor, gastric polyps commonly present with epigastric pain and early satiety. We hereby delineate the case of a middle-aged female who presented with chronic iron deficiency anemia and a positive fecal occult blood test. She underwent an upper endoscopy, which revealed an actively oozing umbilicated lesion in the gastric antrum. Endoscopic ultrasound divulged the submucosal origin of the lesion. It was subsequently excised using endoscopic mucosal resection. Pathologic examination of the resected specimen confirmed the diagnosis of gastric IFP. Furthermore, we conducted a systematic literature search of the MEDLINE database centered on gastric IFPs from January 2000 till March 2020. The data on patient demographics, clinical features, endoscopic findings, lesion site and size, and treatment approaches were collected and analyzed. This article illustrates the overarching need for clinicians to be vigilant of gastric IFPs presenting with initial clinical symptoms suggestive of occult upper gastrointestinal bleeding. Prompt diagnosis and management of gastric IFPs carry paramount importance to combat chronic unexplained iron deficiency anemia following occult bleeding in such patients. A concoction of endoscopy, biopsy, and immunohistochemical examination can be employed toward their prompt detection. Although gastric IFPs have conventionally been treated with surgery, endoscopic resection is now emerging as a safe and efficient therapeutic modality.

Cytomorphologic features of malignant solitary fibrous tumor with mediastinal involvement sampled by endoscopic and endobronchial ultrasound-guided fine-needle aspiration: A comparison of two cases

Solitary fibrous tumor (SFT) is an uncommon fibroblastic neoplasm with considerable risk of local recurrence. SFT is histologically characterized by bland spindled-to-epithelioid cells in alternating hyper- and hypocellular zones, a "patternless pattern," ectatic "staghorn" vessels with variable edematous perivascular stroma, and thick ropey collagen. Cytologically, smears are variably cellular with spindled-to-epithelioid cells with oval nuclei, wispy cytoplasm, multiple inconspicuous nucleoli, and occasional nuclear pseudoinclusions. Small vessels and bare/stripped nuclei are generally present while mild atypia is not uncommon. STAT6 nuclear expression is the most useful immunohistochemical stain and is the product of a NAB2-STAT6 gene fusion. SFTs with mediastinal involvement may be diagnostically challenging due to proximity to vital structures and anticipated patient risks. Endobronchial and endoscopic ultrasound-guided fine-needle aspiration (EBUS/EUS-FNA) are minimally-invasive tissue sampling methods that provide diagnostic material while minimizing patient risk, and the mediastinum is accessible by both procedures. Small aspirate samples and SFT nonspecific features can compound the diagnostic difficulty, although familiarity with the cytologic, morphologic, immunophenotypic, and genetic features of SFTs assist the pathologist in confirming the diagnosis. Pathologists must also be aware of high-risk SFT features to ensure appropriate therapy and management. Case #1 describes a recurrent mediastinal SFT with high-risk features sampled by EUS-FNA. Case #2 describes a primary diagnosis of mediastinal SFT with malignant behavior made on an EBUS-FNA specimen.

Gastric Solitary Fibrous Tumor Causing Upper Gastrointestinal Bleeding

We present an 81-year-old woman with remote breast cancer who presented with melena and hemorrhagic shock requiring intensive care hospitalization. Endoscopic evaluation showed a 5-cm pedunculated gastric mass with ulceration and friability. She underwent sleeve gastrectomy for definitive treatment of her bleeding. Pathology was consistent with a solitary fibrous tumor (SFT). There are only a few reported cases of gastric SFTs presenting with gastrointestinal bleeding. If a large brown/tan bleeding mass is identified on upper endoscopy, SFT should be considered.

Gastric aggressive fibromatosis: report of a case and review of the literature

OBJECTIVES

To describe a rare case of aggressive fibromatosis of the stomach and discuss the differential diagnoses.

METHODS

A 47-year-old man presented with nonspecific abdominal pain. Gastroscopy revealed stomach wall swelling. An antral gastrectomy was performed. Histological examination revealed spindle-shaped cells and morphology typical of aggressive fibromatosis. We performed a literature search to identify conditions with features similar to those of aggressive fibromatosis.

RESULTS

Aggressive fibromatosis does not metastasize, but it is locally invasive and has a tendency to relapse; however, our patient has not had recurrence > 1 year after surgery. Aggressive fibromatosis of the stomach may be confused with an inflammatory fibroid polyp, a gastrointestinal stromal tumor, schwannoma, leiomyoma, inflammatory myofibroblastic tumor, scirrhous carcinoma of the stomach, follicular dendritic cell sarcoma, inflammatory malignant fibrous histiocytoma, myofibroma/myofibromatosis, and solitary fibrous tumor of the stomach.

CONCLUSIONS

Aggressive fibromatosis of the stomach is a rare spindle cell tumor that must be differentiated from a variety of conditions.

Solitary fibrous tumor of the stomach with high-grade sarcomatous dedifferentiation

Solitary fibrous tumors (SFT) are uncommon fibroblastic mesenchymal neoplasms that display a wide range of histologic behaviors. These tumors, which are estimated to account for 2% of all soft tissue neoplasms, typically follow a benign clinical course. However, it is estimated that 10-30% of SFTs are malignant and demonstrate aggressive behavior with local recurrence and metastasis up to several years after surgical resection. We report a case of SFT arising from the stomach, which is an exceptionally rare finding and has been reported only six times in the literature. Our case was complicated by diagnostic dilemma with GIST, highlighting the challenges of diagnosing and characterizing SFTs. Additionally, this tumor was associated with dedifferentiation into undifferentiated pleomorphic sarcoma. To our knowledge, there are no documented cases of a malignant SFT arising from the stomach to demonstrate dedifferentiation into an undifferentiated pleomorphic sarcoma.