Gain-of-function PDGFRA mutations, earlier reported in gastrointestinal stromal tumors, are common in small intestinal inflammatory fibroid polyps. A study of 60 cases

Non-gastrointestinal stromal tumor, mesenchymal neoplasms of the gastrointestinal tract: a review of tumor genetics, pathology, and cross-sectional imaging findings

There is a diverse group of non-gastrointestinal stromal tumor (GIST), mesenchymal neoplasms of the gastrointestinal (GI) tract that demonstrate characteristic pathology and histogenesis as well as variable imaging findings and biological behavior. Recent advancements in tumor genetics have unveiled specific abnormalities associated with certain tumors, influencing their molecular pathogenesis, biology, response to treatment, and prognosis. Notably, giant fibrovascular polyps of the esophagus, identified through MDM2 gene amplifications, are now classified as liposarcomas. Some tumors exhibit distinctive patterns of disease distribution. Glomus tumors and plexiform fibromyxomas exhibit a pronounced affinity for the gastric antrum. In contrast, smooth muscle tumors within the GI tract are predominantly found in the esophagus and colorectum, surpassing the incidence of GISTs in these locations. Surgical resection suffices for symptomatic benign tumors; multimodality treatment may be necessary for frank sarcomas. This article aims to elucidate the cross-sectional imaging findings associated with a wide spectrum of these tumors, providing insights that align with their histopathological features.

Gastrointestinal Tract Challenges: Chronic Inflammatory Fibroid Polyps Demystified

An inflammatory fibroid polyp (IFP), also known as Vanek's tumor, is an uncommon benign tumor typically found as a solitary, intraluminal polyp in the gastrointestinal (GI) tract. Chronic IFP is characterized by persistent or recurrent inflammatory features, distinct histopathological findings, and a potential for significant GI tract involvement. Typically, IFPs occur predominantly in the gastric antrum, small intestines, and recto-sigmoid colon. They initiate within the submucosal layer and extend into the lamina propria, resulting in a noticeable bulging of the mucosal layer. They may breach the mucosal barrier on rare occasions, leading to ulceration and bleeding. This ongoing bleeding can induce persistent blood loss and symptoms typical of hypovolemic shock. When of smaller size, these growths might be accidentally detected during an endoscopic examination. Conversely, if the lesions are sizable, they can prompt symptoms of obstruction like queasiness, retching, and abdominal discomfort. Here, we present a case of a 47-year-old female who underwent a screening colonoscopy and was found to have an IFP.

A Rare PDGFRA Exon 15 Germline Mutation Identified in a Patient With Phenotypic Manifestations Concerning for GIST-Plus Syndrome: A Case Report and Review of Literature

Molecular alterations in PDGFRA are well-described as drivers of sporadic gastrointestinal stromal tumors (GISTs) and inflammatory fibroid polyps (IFPs). However, a small number of families with germline PDGFRA mutations in exons 12, 14, and 18 have been reported, forming the basis of an autosomal dominant inherited disorder with incomplete penetrance and variable expressivity, now referred to as PDGFRA-mutant syndrome or GIST-plus syndrome. Phenotypic manifestations of this rare syndrome include multiple gastrointestinal GISTS, IFPs, fibrous tumors, and other variable features. Herein, we report the case of a 58-year-old female who presented with a gastric GIST and numerous small intestinal IFPs, found to harbor a previously undescribed germline PDGFRA exon 15 p.G680R mutation. Somatic tumor testing was performed on the GIST, a duodenal IFP, and an ileal IFP utilizing a targeted next-generation sequencing panel, revealing additional and distinct secondary PDGFRA exon 12 somatic mutations in each of the 3 tumors. Our findings raise important considerations regarding mechanisms of tumor development in patients with underlying germline PDGFRA alterations and highlight the potential utility of expanding currently available germline and somatic testing panels to include exons outside the typical hotspot regions.

Identification of an Activating PDGFRA Deletion in a Novel Sinonasal Soft Tissue Neoplasm

BACKGROUND

Spindle cell tumours in the sinonasal area are diagnostically challenging. We identified a neoplasm that defied histopathological classification using current criteria.

METHODS

The case was subjected to histopathological, immunohistochemical and molecular analysis using a large small variant DNA panel.

RESULTS

The tumour comprised cytologically bland epithelioid spindle cells with a rich vasculature, which lack expression of actin and other smooth muscle markers, CD34 and beta-catenin. An activating insertion/deletion in exon 12 of the PDGFRA gene was detected. This alteration has previously been described in gastrointestinal stromal tumours and inflammatory fibroid polyps of the GI tract, but the site, histological, and immunophenotypic features in this tumour are distinct.

CONCLUSION

We describe a novel sinonasal spindle cell tumour characterised by an activating insertion/deletion in exon 12 of PDGFRA. The diagnosis of PDGFRA-activated sinonasal spindle cell tumour should be considered in difficult to classify mesenchymal lesions at this site.

Jejunal Intussusception Secondary to a Large Inflammatory Fibroid Polyp: A Case Report and Discussion of Differential Diagnosis

Inflammatory fibroid polyp (IFP), initially considered a reactive process, is now recognized as a benign mesenchymal neoplasm of the gastrointestinal tract. We report a case of a 68-year-old woman with medically refractory Crohn disease that presented with intussusception requiring surgical intervention. The resection revealed a jejunal mass consisting of a submucosal proliferation of bland spindle cells in a fibrous stroma infiltrated by numerous eosinophils. By immunohistochemistry, the lesion was positive for vimentin and negative for desmin, smooth muscle actin (SMA), S-100, CD117, DOG1, ALK (D5F3), Melan-A, HMB-45, CD34, and STAT6. Ki-67 proliferative index was low (<1%). The mass was classified as IFP by its characteristic morphology and associated eosinophilia. IFP should be considered in the differential diagnosis of adults with intussusception or bowel obstruction. Definitive treatment typically requires surgical resection of the involved bowel segment.

Inflammatory fibroid polyp of the anus in a 12-month-old girl: Case report and review of the literature

Inflammatory fibroid polyp (IFP) is a rare, usually solitary and intraluminal polypoid benign tumour that can affect any part of the gastrointestinal (GI) tract. Its aetiology is unknown and clinical presentation depends on the site of involvement. We present the case of a 12-month-old girl with IFP and review all reported cases of IFP in children and adolescents <18 years. A 12-month-old girl presented with rectal bleeding. The patient underwent colonoscopy which revealed an anus polyp. Surgical resection was performed and histopathological examination of the specimen showed features of IFP. A literature review of 20 cases (including ours) between 1966 and January 2022 is also presented. To our knowledge, this is the youngest reported patient with IFP and the first in the anal area.

[Mesenchymal tumors and tumor-like lesions of the gastrointestinal tract: an overview]

Mesenchymal tumors and tumor-like lesions of the gastrointestinal (GI) tract are uncommon. They vary from reactive tumefactive lesions and benign neoplasms to highly aggressive sarcomas. Among them, GI stromal tumors (GISTs) are most common, followed, with less frequency, by smooth muscle and neurogenic tumors. The major challenge resides in correctly identifying GISTs and providing a comprehensive report (including risk assessment and genotyping) that represents the basis for an optimized surgical-oncological treatment and/or adjuvant therapy. On the other hand, the challenge of benign lesions is to find a good name (well understandable and reproducible diagnostic term) that helps avoid diagnostic ambiguity and prognostic uncertainty so that overprognostication and overtreatment can be prevented. Moreover, several recently described genetically defined benign and malignant entities need be correctly diagnosed due to their special "targeted" therapeutic options and to further characterize their clinicopathological and biological properties in the future. These recent entities include aggressive epithelioid inflammatory myofibroblastic sarcoma (ALK-RANBP2-driven), malignant gastrointestinal neuroectodermal tumor (EWSR1-ATF1/CREB-related), NTRK-rearranged neoplasms, and, most recently, colorectal NUTM1-rearranged sarcomas. This review highlights the major clinicopathological features of gastrointestinal mesenchymal lesions in light of recent developments.

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.

PDGFRA Immunohistochemistry Predicts PDGFRA Mutations in Gastrointestinal Stromal Tumors

Platelet-derived growth factor receptor A (PDGFRA) is a receptor tyrosine kinase that is activated by mutations in 10% of gastrointestinal stromal tumors (GISTs) and 55% to 70% of inflammatory fibroid polyps. PDGFRA-mutant GISTs are usually epithelioid and occur predominantly in the stomach. Succinate dehydrogenase-deficient GISTs also arise in the stomach and are usually epithelioid, as are some KIT-mutant GISTs. Recently, avapritinib was approved to treat PDGFRA D842V-mutant GISTs, which do not respond to conventional targeted therapy. Here, we evaluate the utility of PDGFRA immunohistochemistry (IHC) to predict PDGFRA mutations to direct targeted therapy. PDGFRA IHC was performed at 1:3000 and 1:10,000 dilutions on a tissue microarray containing 153 GISTs (126 KIT-mutant, 17 PDGFRA-mutant, and 10 succinate dehydrogenase-deficient). The "positive" staining threshold was defined as 50% of neoplastic cells staining at moderate intensity. PDGFRA IHC was 75.0% and 80.9% specific for PDGFRA mutations at 1:3000 and 1:10,000 dilutions, respectively, and it was 100% sensitive at both. On the basis of its higher specificity, a 1:10,000 dilution was used to stain whole-tissue sections of GISTs and other gastric tumor types. Combining tissue microarray and whole-tissue data, PDGFRA IHC was 94.4% sensitive and 81.0% specific for PDGFRA-mutant GIST among all 210 GISTs, and it was 84.1% specific among 149 GISTs with an epithelioid component. PDGFRA was positive in a subset of inflammatory fibroid polyps (15/30; 50%), monophasic synovial sarcomas (5/10; 50%), inflammatory myofibroblastic tumors (5/10; 50%), and plexiform fibromyxomas (2/8; 25%). It was negative in poorly differentiated adenocarcinoma (0/20), diffuse large B-cell lymphoma (0/10), glomus tumor (0/10), gastrointestinal neuroectodermal tumor (0/10), leiomyoma (0/10), gastric schwannoma (0/8), and gastroblastoma (0/3). Among GISTs, PDGFRA IHC is highly sensitive and moderately specific for PDGFRA-mutant tumors; it also can be positive in inflammatory fibroid polyp and some other mesenchymal tumor types. PDGFRA positivity could be used to triage epithelioid GISTs for PDGFRA sequencing to determine optimal therapy.

PDGF receptor mutations in human diseases

PDGFRA and PDGFRB are classical proto-oncogenes that encode receptor tyrosine kinases responding to platelet-derived growth factor (PDGF). PDGFRA mutations are found in gastrointestinal stromal tumors (GISTs), inflammatory fibroid polyps and gliomas, and PDGFRB mutations drive myofibroma development. In addition, chromosomal rearrangement of either gene causes myeloid neoplasms associated with hypereosinophilia. Recently, mutations in PDGFRB were linked to several noncancerous diseases. Germline heterozygous variants that reduce receptor activity have been identified in primary familial brain calcification, whereas gain-of-function mutants are present in patients with fusiform aneurysms, Kosaki overgrowth syndrome or Penttinen premature aging syndrome. Functional analysis of these variants has led to the preclinical validation of tyrosine kinase inhibitors targeting PDGF receptors, such as imatinib, as a treatment for some of these conditions. This review summarizes the rapidly expanding knowledge in this field.

Jejunojejunal intussusception secondary to inflammatory fibroid polyp: A rare cause of small bowel obstruction

Background

Adult intussusception is a relatively rare clinical entity. The majority of cases of intussusception in adults are due to a pathologic condition that serves as a lead point and requires surgery. Small bowel intussusception is usually caused by benign or malignant neoplasms appearing at the head of the invagination. Inflammatory fibroid polyp (IFP) of the small bowel is an unusual benign neoplastic lesion that has been rarely reported to cause intussusception, especially in the jejunum.

Case presentation

We present a rare case of adult intussusception who presented with a triad of intestinal obstruction. Computed tomography revealed small bowel intussusception with bowel ischemia. Intraoperatively, she required resection of the small bowel and primary anastomosis. Macroscopic examination revealed a single pedunculated polyp, which is the lead point of intestinal obstruction and confirmed histologically.

Conclusion

Inflammatory fibroid polyp should be considered as a cause of intussusception among adults with small bowel obstruction.

Inflammatory Fibroid Polyp: An Unusual Cause of Abdominal Pain in the Upper Gastrointestinal Tract a Case Report

Inflammatory fibroid polyps (IFPs) tend to occur in the gastrointestinal tract, and they are rare and benign neoplasms. In general, IFPs often come from epithelial tissue. The gastric antrum is the most common location. Endoscopic ultrasound (EUS) often shows a predominantly hypoechoic mass with well-defined borders originating from the submucosal area. Here, we report the case of a 46-year-old woman with abdominal pain who underwent computed tomography (CT), endoscopic ultrasound and endoscopic submucosal dissection (ESD) of resected specimens; the diagnosis was ultimately an inflammatory fibroid polyp. She is currently in clinical remission.

Inflammatory Fibroid Polyp in a 48-Year-Old Male: A Rare Cause of Intussusception

Inflammatory fibroid polyp is a neoplastic condition affecting the gastrointestinal tract and particularly the gastric antrum. It is virtually a benign submucosal mass comprising mesenchymal cells and numerous small blood vessels with inflammatory cells and commonly eosinophils. Patients with inflammatory fibroid polyps usually present clinically with mechanical intestinal obstruction with or without intussusception. Herein, we present a case of a 48-year-old male with a known history of schizophrenia who presented with mechanical intestinal obstruction following intussusception due to inflammatory fibroid polyp involving the proximal jejunojejunal part of the jejunum.

Masquerading in the midgut: a rare diagnosis in a patient with recurrent abdominal pain

A 38-year-old woman who had been previously diagnosed with irritable bowel syndrome was seen in the outpatient clinic with a 2-year history of intermittent cramp-like abdominal pain which was often followed by watery diarrhoea. She had presented several times previously to the emergency department with episodes of severe pain and collapse although on arrival examination findings were mostly unremarkable other than some mild lower abdominal tenderness. On each occasion, the symptoms resolved spontaneously with conservative management. She had been extensively investigated by her general practitioner to establish the cause of her symptoms but all laboratory findings, cross-sectional imaging, ultrasound and oesophagogastroduodenoscopy to date were unremarkable. After being seen in gastroenterology outpatients' clinic, a colonoscopy was performed and was described as being macroscopically normal but microscopic evaluation of colonic biopsies suggested a possible 'resolving infection'. She was treated symptomatically, but within 6 months she represented to hospital with progressively worsening symptoms of severe abdominal pain, now associated with vomiting, followed by watery diarrhoea and then resolution of the symptoms. An abdominal CT scan was performed which showed a small intraluminal-filling defect in the mid-terminal ileum. A wireless capsule endoscopy was organised to further characterise the lesion although this was reported as showing no abnormality. Prior to any further outpatient investigations, she represented as an emergency to hospital in small bowel obstruction, underwent further cross-sectional imaging followed by surgical resection of the lesion. Histological characterisation revealed a small bowel inflammatory fibroid polyp.

A large inflammatory fibroid polyp of the rectum removed by transanal excision

Inflammatory fibroid polyps (IFP) are rare benign lesions arising from the submucosa of the gastrointestinal tract, most commonly found in the stomach and small intestine. IFPs are very rarely found in the rectum, with only a few reported cases, and their presentation is quite varied. The patient is a 53 year old male who underwent routine screening colonoscopy, during which a lobular mass of the proximal rectum was discovered. The patient subsequently underwent an endoscopic ultrasound (EUS) with fine needle aspiration (FNA) biopsy. Pathology displayed scant spindle cells with benign glandular epithelium suspicious for a spindle cell neoplasm. The mass was excised transanally. The morphological and immunohistochemical findings supported the diagnosis of inflammatory fibroid polyp. Although this is not a malignant tumor, the treatment and surveillance guidelines have not been determined and there is no standard of care.

Telocytes are the physiological counterpart of inflammatory fibroid polyps and PDGFRA-mutant GISTs

PDGFRA mutations in the gastrointestinal (GI) tract can cause GI stromal tumour (GIST) and inflammatory fibroid polyp (IFP). Hitherto no cell type has been identified as a physiological counterpart of the latter, while interstitial Cajal cells (ICC) are considered the precursor of the former. However, ICC hyperplasia (ICCH), which strongly supports the ICC role in GIST pathogenesis, has been identified in germline KIT-mutant settings but not in PDGFRA-mutant ones, challenging the precursor role of ICC for PDGFRA-driven GISTs. Telocytes are a recently described interstitial cell type, CD34+/PDGFRA+. Formerly considered fibroblasts, they are found in many organs, including the GI tract where they are thought to be involved in neurotransmission. Alongside IFPs and gastric GISTs, GI wall "fibrosis" has been reported in germline PDGFRA-mutants. Taking the opportunity offered by its presence in a germline PDGFRA-mutant individual, we demonstrate that this lesion is sustained by hyperplastic telocytes, constituting the PDGFRA-mutant counterpart of germline KIT mutation-associated ICCH. Moreover, our findings support a pathogenetic relationship between telocyte hyperplasia and both IFPs and PDGFRA-mutant GISTs. We propose the term "telocytoma" for defining IFP, as it conveys both the pathogenetic (neoplastic) and histotypic ("telocytary") essence of this tumour, unlike IFP, which rather evokes an inflammatory-hyperplastic lesion.

Invasive inflammatory fibroid polyp of the stomach: a case report and literature review

Background

Inflammatory fibroid polyps (IFPs) are rare mesenchymal lesions that affect the gastrointestinal tract. IFPs are generally considered benign, noninvasive lesions; however, we report a case of an invasive gastric IFP. To the best of our knowledge, this is only the second case report of an invasive gastric IFP.

Case presentation

A 62-year-old woman presented with complaints of epigastric pain and vomiting. Computed tomography showed a 27-mm, hyper-enhancing tumor in the prepyloric antrum. Upper endoscopy also showed a submucosal tumor causing subtotal obstruction of the gastric outlet. Because a gastrointestinal stromal tumor was suspected, distal gastrectomy was performed. Histopathological examination revealed spindle cell proliferation in the submucosal layer. The spindle cells had invaded the muscularis propria layer and extended to the subserosal layer. The tumor was finally diagnosed as an IFP based on immunohistochemical findings. No mutations were identified in the platelet-derived growth factor receptor alpha (PDGFRA) gene via molecular genetic analysis.

Discussion and conclusions

After the discovery that IFPs often harbor PDGFRA mutations, these growths have been considered neoplastic lesions rather than reactive lesions. Based on the present case, IFPs might be considered not only neoplastic but also potentially invasive lesions.

Nonsyndromic Intestinal Lipomas are Probably not Associated With Mutations of PDGFRA

The purpose of this study was to test the hypothesis that intestinal lipomas occurring in patients devoid of signs of PDGFRA-mutant syndrome might represent sporadic counterparts of familial lipomatous tumors occurring in the spectrum of tumors associated with PDGFRA mutations. PDGFRA-mutant syndrome may manifest with gastrointestinal stromal tumors, Vanek tumors, fibrous tumors, and lipomatous tumors. Until now there has been no molecular genetic study of PDGFRA mutations in intestinal lipomas published in the world literature. A series of 20 intestinal lipomas were obtained from 17 patients, and mutational analysis of exons 12, 14, and 18 of the PDGFRA gene was performed. None of the 16 analyzable tumors showed mutations in PDGFRA. Thus, PDGFRA mutations probably do not play an important role in the development of sporadic lipomas of the intestines.

An Unusual Cause of Intestinal Obstruction in a Young Adult Patient: Inflammatory Fibroid Polyp

Inflammatory fibroid polyps are uncommon benign lesions that originate in the submucosa of the gastrointestinal tract. The stomach and the ileum are the most commonly affected sites. Although inflammatory fibroid polyp is one of the rare conditions leading to intestinal obstruction in adults, it should be considered as a possible diagnosis in obstructive tumors of the small bowel causing intussusceptions. We present one case of inflammatory fibroid polyp as a rare cause of intussusception in a young adult patient.

Locally infiltrative inflammatory fibroid polyp of the ileum: report of a case showing transmural proliferation

Morphologically, an inflammatory fibroid polyp (IFP) is usually centred in the submucosa. Extension of an IFP to the subserosa with destruction of the muscularis propria is exceedingly rare. Herein, we describe a 70-year-old woman who presented with right lower abdominal pain but was finally diagnosed with an IFP. Contrast-enhanced computed tomography revealed a target-like structure with a hypovascular mass at the leading edge, which was consistent with intussusception due to a tumour. Following surgery, the resected specimen displayed a mass measuring 4 × 3 × 3 cm that was protruding into the lumen. Microscopically, the mass was centred in the submucosa, extending up to the mucosal surface and down to the subserosa and serosa. The muscularis mucosae and muscularis propria were destroyed focally. A PDGFRA gene mutation in exon 2 (1837_1851 del) that was found in this case, as well as a highly infiltrative growth pattern, strongly supported the neoplastic nature of IFP.

Divergent gastrointestinal stromal tumors in syndromic settings

The vast majority of gastrointestinal stromal tumors (GISTs) occur as sporadic tumors. Rarely, however, these neoplasms can arise in syndromic contexts. Under these circumstances, GISTs are often multiple and associated with accompanying signs peculiar of the hosting syndrome. Moreover, syndromic GISTs themselves tend to show heterogeneous features depending on the underlying condition. Multiple inflammatory fibroid polyps (IFPs) and a jejunal spindle-cell GIST were resected in a germline PDGFRA-mutant individual. Although the association of IFP and GIST is typical of this genetic setting (PDGFRA mutations can in fact trigger both these tumor types), PDGFRA-mutant GISTs are usually epithelioid and gastric. This discrepancy was settled evidencing a somatic KIT mutation in the GIST. The awareness of possible somatic mutations can be critical in the management of high-risk/malignant GISTs arising in syndromic settings. GIST features unusual for a given GIST-predisposing syndrome are a valuable tool in the hands of physicians for suspecting these "extra" triggers, which could not be sought for once a diagnosis of GIST-prone syndrome is well established, in a bona fide cost/benefit perspective.

Inflammatory fibroid polyp (Vanek's tumour): my worst nightmare in the emergency department

A middle-aged woman presented in shock with bleeding per rectum for 2 days without any significant past medical or surgical illness. Abdominal sonography, oesophagogastroduodenoscopy and sigmoidocolonoscopy were unremarkable. Despite 6 units of blood transfusion, 3000 mL of plasma expanders and ionotropes, the arterial pressure gradually decreased. We had no choice but to undergo life-threatening yet possibly life saving laparotomy. We found a 1×1 cm ileal bleeding mucosal polyp about 20 cm away from the ileocaecal junction. We resected and anastomosed end to end. Perioperatively, the patient was transfused with another 4 units of blood product. Immunohistopathology revealed a large number of CD34 positive spindle cells and eosinophils with extensive thick-walled capillaries compatible with inflammatory fibroid polyp. This case of Vanek's tumour is reported for its atypical site, which presented as massive obscure gastrointestinal haemorrhage without any prior warning signs.

Plexiform fibromyxoma with cotyledon-like serosal growth: A case report of a rare gastric tumor and review of the literature

Plexiform fibromyxoma is a rare, benign mesenchymal neoplasm that predilects the gastric antrum and has potential for misdiagnosis as a gastrointestinal stromal tumor (GIST). The histology of the tumor is characterized by interwoven fascicular growth of cytologically bland spindled cells within a variably myxoid stroma. The current study reports the clinicopathological and immunohistochemical findings of a plexiform fibromyxoma resected from a 28-year-old Vietnamese female. The patient presented with acute, severe abdominal pain and worsening anemia. The initial fine-needle aspiration and needle core biopsy of the gastric antral mass led to an initial diagnosis of GIST. The subsequent distal partial gastrectomy revealed a 5.5-cm transmural antral mass that ulcerated the overlying mucosa and grew as variably elongated, myxoedematous, polypoid (cotyledon-like) excrescences from the serosal surface. Microscopically, the tumor demonstrated plexiform and multinodular growth of cytologically bland spindled cells proliferating in an abundant myxocollagenous stroma with a prominent capillary network. Tumor cells immunohistochemically expressed smooth muscle actin and CD10, but did not express CD117, Discovered on GIST-1 or nuclear β-catenin. Follow-up evaluation 23 months post surgery revealed no evidence of residual tumor. A review the cases of this rare entity reported in the English language literature is also provided.

PDGFRA-mutant syndrome

Germline PDGFRA mutations cause multiple heterogeneous gastrointestinal mesenchymal tumors. In its familial form this disease, which was formerly termed intestinal neurofibromatosis/neurofibromatosis 3b (INF/NF3b), has been included among familial gastrointestinal stromal tumors (GISTs) because of its genotype, described when GIST was the only known PDGFRA-mutant gastrointestinal tumor. Shortly afterwards, however, inflammatory fibroid polyps also revealed PDGFRA mutations. Subsequently, gastrointestinal CD34+ 'fibrous tumors' of uncertain classification were described in a germline PDGFRA-mutant context. Our aim was to characterize the syndrome produced by germline PDGFRA mutations and establish diagnostic criteria and management strategies for this hitherto puzzling disease. We studied a kindred displaying multiple gastrointestinal mesenchymal tumors, comparing it with published families/individuals with possible analogous conditions. We identified a novel inherited PDGFRA mutation (P653L), constituting the third reported example of familial PDGFRA mutation. In adult mutants we detected inflammatory fibroid polyps, gastric GISTs and gastrointestinal fibrous tumors of uncertain nosology. We demonstrate that the syndrome formerly defined as INF/NF3b (exemplified by the family reported herein) is simplistically considered a form of familial GIST, because inflammatory fibroid polyps often prevail. Fibrous tumors appear variants of inflammatory fibroid polyps. 'INF/NF3b' and 'familial GIST' are misleading terms which we propose changing to 'PDGFRA-mutant syndrome'. In this condition, unlike KIT-dependent familial GIST syndromes, if present, GISTs are stomach-restricted and diffuse Cajal cell hyperplasia is not observed. This restriction of GISTs to the stomach in PDGFRA-mutant syndrome: (i) focuses oncological concern on gastric masses, as inflammatory fibroid polyps are benign; (ii) supports a selective role of gastric environment for PDGFRA mutations to elicit GISTs, justifying the known predilection for stomach of sporadic PDGFRA-mutant GISTs. An awareness that inflammatory fibroid polyps, relatively common among gastrointestinal mesenchymal tumors, may be the prevailing tumor in PDGFRA-mutant syndrome could eventually reveal an unsuspected prevalence of this condition.

Vanek’s tumor of the small bowel in adults

Inflammatory fibroid polyps (IFPs), or Vanek’s tumor, are one of the least common benign small bowel tumors. IFP affects both sexes and all age groups, with a peak of incidence in the fifth and seventh decades. They can be found throughout the gastrointestinal tract but most commonly in the gastric antrum or ileum. The underlying cause of IFPs is still unknown. Genetic study of IFP showed mutations in platelet derived growth factor alpha in some cases. At the time of diagnosis most IFPs have a diameter of 3 to 4 cm. The lesions have always been recorded as solitary polyps. Symptoms depend on the location and the size of the lesion, including abdominal pain, vomiting, altered small bowel movements, gastrointestinal bleeding and loss of weight. IFPs arising below the Treitz ligament can present with an acute abdomen, usually due to intussusceptions. Abdominal computed tomography is currently considered the most sensitive radiological method to show the polyp or to confirm intussusceptions. Most inflammatory fibroid polyps can be removed by endoscopy. Surgery is rarely needed. Exploratory laparoscopy or laparotomy is frequently recommended as the best treatment for intussusceptions caused by IFP. The operation should be performed as early as possible in order to prevent the intussusceptions from leading to ischemia, necrosis and subsequent perforation of the invaginated bowel segment. This report aims at reviewing the diagnosis, etiology, genetics, clinical presentation, endoscopy, radiology, and best treatment of IFP.

A Large Gastric Inflammatory Fibroid Polyp

Inflammatory fibroid polyp (IFP) is an unusual benign gastrointestinal subepithelial tumor (SET). The endosonographic (EUS) features of IFPs were sporadically reported on imaging tips or small case series study. However, the differential diagnosis and optimal treatment of gastric IFP is still challenging. We report an unusual case of a large erosioned and prolapsing gastric submucosal lesion, presenting primarily with obstructive symptoms ("ball valve syndrome") and anemia. On EUS examination, a 50 mm SET in the distal antrum was seen, with hypoechoic but heterogeneous echo-pattern, located in the second and third sonographic layers of the gastric wall (deep mucosal and submucosal). The fourth (muscle) layer was intact; no peri-lesional adenopathies were identified. A decision was made to proceed to endoscopic treatment because of the mentioned symptoms. Histopathologic evaluation of the resected specimen with immunohistochemical staining was consistent with the diagnosis of IFP. IFP rarely reach these large dimensions or cause symptoms. Despite its benign etiology, endoscopic resection was important in both establishing a histologic diagnosis and treatment. EUS was crucial in the differential diagnosis. The literature concerning IFP is also reviewed.

[Intra-abdominal soft tissue tumors. What needs to be known to reach the diagnosis with the help of immunohistochemistry, FISH and molecular biology]

Connective tissue tumors located inside the abdomen are a rare heterogeneous group of tumors, except for gastro-intestinal stromal tumors. They may be benign, malignant, or intermediate in terms of biologic potential. Pathologists have to remember the list of all the lesions possibly involved, with their immunohistochemical characteristics, and to know which molecular analyses are needed, with which expected results, and by which team they can be performed. The main tumor types are discussed with diagnostic tools and treatment consequences.

An unusual presentation of an inflammatory fibroid polyp of the ileum: A case report

Inflammatory fibroid polyps (IFP) are rare, benign lesions of the gastrointestinal tract. Recent molecular studies of IFPs identified platelet-derived growth factor receptor α (PDGFRA)-activating mutations, suggesting possible neoplastic qualities to IFPs. IFPs originate from the submucosa and often extend into the overlying mucosa. Although certain IFPs infiltrate the muscularis propria focally, disruption of the muscularis propria and penetration into the subserosa is extremely rare. The current study presents an unusual case of an ileal IFP. A 48-year-old female visited the Department of Surgery, Chonbuk National University Hospital (Jeonju, Republic of Korea) due to abdominal pain. Radiological study demonstrated an ileocecal-type intussusception due to a luminal polypoid mass of the ileum. The excised tumor consisted of haphazardly arranged epithelioid and spindled cells in a fibromyxoid stroma, with an abundant vascular network, accompanied by an inflammatory reaction predominantly composed of eosinophilic infiltrates. The infiltrating tumor cells disrupted the muscularis mucosa above the tumor cells and the muscularis propria below the tumor cells, and extended into the subserosa. Immunohistochemically, the tumor cells were positive for vimentin and cluster of differentiation 34, while they were negative for keratin, PDGFRA, smooth muscle actin, desmin, S-100 protein, DOG-1 and c-kit. Sequencing analysis of c-kit exons 9, 11, 13 and 17, and PDGFRA exons 12 and 18 indicated a wild-type status. The patient has remained well for 12 months after surgery without further treatment, with no recurrence of the tumor. Although spread of IFP under the muscularis propria is rare, identification of similar cases and further study will enhance our understanding of the nature of this tumor.

Recurrent adult jejuno-jejunal intussusception due to inflammatory fibroid polyp - Vanek's tumour: a case report

Background

Adult intussusception is a rare but challenging condition. Preoperative diagnosis is frequently missed or delayed because of nonspecific or sub-acute symptoms.

Case presentation

We present the case of a sixty-two year old gentleman who initially presented with pseudo-obstruction. Computerised tomography displayed a jejuno-jejunal intussusception, which was treated by primary laparoscopic reduction. The patient re-presented with acute small bowel obstruction two weeks later. He underwent a laparotomy showing recurrent intussusception and required a small bowel resection with primary anastomosis. Histological examination of the specimen revealed that the intussusception lead point was due to an inflammatory fibroid polyp (Vanek’s tumour) causing double invagination.

Conclusions

Adult intussusception presents with a variety of acute, intermittent, and chronic symptoms, thus making its preoperative diagnosis difficult. Although computed tomography is useful in confirming an anatomical abnormality, final diagnosis requires histopathological analysis. Vanek’s tumours arising within the small bowel rarely present with obstruction or intussusception. The optimal surgical management of adult small bowel intussusception varies between reduction and resection. Reduction can be attempted in small bowel intussusceptions provided that the segment involved is viable and malignancy is not suspected.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/7292185123639943

Do Not Be Fooled by Fancy Mutations: Inflammatory Fibroid Polyps Can Harbor Mutations Similar to Those Found in GIST

Goal. Surgeons that remove a typical polyp from the stomach or small intestine should be reluctant to accept a diagnosis of GIST just because there is a mutation in platelet-derived growth factor receptor alfa (PDGFRA). Background. A subtype of gastric and intestinal polyps is denoted as inflammatory fibroid polyp (IFP). In some of these cases a mutation in PDGFRA is found, leading to the diagnosis of gastrointestinal stromal tumor (GIST). Study. This study includes two patients that had polyps removed from the ileum, and an extended investigation was performed with immunohistochemical staining and mutation analyses. Results. The tumors did not show typical immunohistochemical staining for markers used to diagnose GIST, but the mutation analysis revealed a mutation in PDGFRA exon 12. On the basis of the mutation analysis, both polyps were primarily diagnosed as GISTs, but the diagnosis was later changed to inflammatory fibroid polyp. Conclusion. It is important that both surgeons and pathologists be aware that IFP can harbor a mutation in PDGFRA where further treatment and follow-up is different with the two different diagnoses. A mutation analysis can be misleading when taken out of the context of clinical observations, histological characteristics and immunohistochemical staining.

Inflammatory fibroid polyp: a rare benign tumor of the alimentary tract in children presenting as intussusception-case report and review of literature

Inflammatory fibroid polyp (IFP) represents a rare cause of gastrointestinal polypoid disease in childhood. Τhe lesion has been described by various names beyond the currently accepted term, including “Vanek's tumour,” eosinophilic or submucosal granuloma, gastric fibroma with eosinophilic infiltration, inflammatory pseudotumor, and hemangiopericytoma. The etiopathogenesis and origin of the mesenchymal spindle-shaped cells that comprise the polyp remains enigmatic. Recent studies have shown familial occurrence, expression of platelet-derived growth factor receptor (PDGFRA) and oncogenic PDGFRA mutations in the majority of lesions, suggestive of a neoplastic nature. We present a rare case of a 10-year-old boy with an IFP of the terminal ileum, who presented acutely with intussusception and was treated with a right hemicolectomy. Postoperative course was uneventful and the patient has been asymptomatic during follow-up. Histopathology and immunohistochemical analysis excluded inflammatory myofibroblastic tumor (negative for Alk1, desmin, smooth muscle actin [SMA]), gastrointerstinal stromal tumors (GIST) (negative for CD117) and schwannoma (negative for S100). The lesion was positive for CD34 and faintly for vimentin. Despite the classification of IFPs as a mesenchymal benign neoplasm, in the vast majority of cases, surgical excision alone was curative, and no reports exist of a malignant transformation. A cautious approach with periodic surveillance of the affected children seems reasonable though.

Mesenchymal Tumors of the Gastrointestinal Tract Other than GIST

Mesenchymal tumors involve the gastrointestinal (GI) tract more frequently than other visceral organs. Many such tumors are small, and are benign and increasingly being detected incidentally during colonoscopic screening. Some tumors show distinctive features at this site, such as schwannoma and clear cell sarcoma-like tumor of the GI tract. Without knowledge of these features, recognition of these tumor types can be difficult. This reviews addresses recent developments and diagnostic features of mesenchymal tumors of the GI tract other than gastrointestinal stromal tumor (GIST).

Gastrointestinal stromal tumor

Gastrointestinal stromal tumor has received a lot of attention over the last 10 years due to its unique biologic behavior, clinicopathological features, molecular mechanisms, and treatment implications. GIST is the most common mesenchymal neoplasm in the gastrointestinal tract and has emerged from a poorly understood and treatment resistant neoplasm to a well-defined tumor entity since the discovery of particular molecular abnormalities, KIT and PDGFRA gene mutations. The understanding of GIST biology at the molecular level promised the development of novel treatment modalities. Diagnosis of GIST depends on the integrity of histology, immunohistochemistry and molecular analysis. The risk assessment of the tumor behavior relies heavily on pathological evaluation and significantly impacts clinical management. In this review, historic review, epidemiology, pathogenesis and genetics, diagnosis, role of molecular analysis, prognostic factor and treatment strategies have been discussed.

Inflammatory Fibroid Polyp in the Duodenum of a Common Marmoset (Callithrix jacchus)

A 32-month-old male common marmoset had a firm and white-colored mass in the duodenal wall. The cut surface was smooth and grayish white in color. Histologically, the mass consisted of a proliferation of spindle cells with an oval to spindle-shaped nucleus and scant eosinophilic cytoplasm in a loose myxoid or fibrotic background. Most of the lesion displayed no specific growth pattern whereas some of the cells concentrated around the vessels and created an onion-bulb structure. Additionally, marked inflammatory cellular infiltration, mainly eosinophils, was observed throughout the lesion. Immunohistochemically, the spindle cells were positive for vimentin, α-smooth muscle actin, fascin, and cyclin D1, and negative for S-100, factor VIII–related antigen, and c-kit. These histological and immunohistochemical features did not meet any differential diagnoses such as gastrointestinal stromal tumor, inflammatory myofibroblastic tumor, solitary fibrous tumor/hemangiopericytoma, smooth muscle tumor, schwannoma, and hemangiosarcoma. Collectively, the authors diagnosed the mass as a lesion that corresponded to an inflammatory fibroid polyp (IFP) in humans. IFP is defined as a mesenchymal proliferation composed of spindle stromal cells, small blood vessels, and inflammatory cells, particularly eosinophils, and is currently classified as a nonneoplastic lesion. To the best of our knowledge, this is the first case of spontaneous IFP in nonhuman primates.

Clinicopathologic features of inflammatory fibroid polyp of the esophagus

AIM: To explore the clinical and pathological features of inflammatory fibroid polyp (IFP) of the esophagus and to discuss its diagnosis, differential diagnosis, treatment and prognosis.

METHODS: A case of IFP of the esophagus was investigated by light microscopy and immunohistochemistry. A literature review was then performed to summarize the clinical and pathological features of the disease.

RESULTS: A 71-year-old man presented with epigastric/retrosternal pain and dysphagia for 3 months. Endoscopy revealed a hemispheric lesion, 2.5 cm in size, in the esophageal mucosa about 35 cm from incisors. On EUS, the lesion (13.2 mm x 11 mm) was hypoechogenic and inhomogeneous, and was located under the mucosa of the esophagus, with a clear boundary. Surgical resection of the esophageal mass was performed, and the final pathologic diagnosis was IFP of the esophagus.

CONCLUSION: IFP of the esophagus is an extremely rare mesenchymal tumor with benign behavior and good prognosis. A correct preoperative diagnosis is difficult and relies on postoperative pathological examination. Surgical excision is the preferred treatment for IFP.

Activating PDGFRA mutations in inflammatory fibroid polyps occur in exons 12, 14 and 18 and are associated with tumour localization

AIMS

Inflammatory fibroid polyps (IFP) are mesenchymal tumours of the gastrointestinal tract. This study was performed to broaden the base of evidence of the pathogenic role of PDGFR mutations in IFP with particular regard to clinicopathological data and mutational patterns among IFP subtypes.

METHODS AND RESULTS

Molecular analysis of 38 tumours revealed activating mutations in three different exons of PDGFRA in 25 IFP. For the first time we report two cases with PDGFRA-exon 14 mutations (p.N659K; p.[N659K(+)T665A]). The results of our study and cases reported earlier indicate clearly that there is a localization-specific pattern: exon 12 mutations predominate in the small intestine, while exon 18 mutations occur frequently in the stomach (P < 0.001). Codons 567-571 of PDGFRA represent an IFP specific mutational hot spot and are affected most frequently by deletions. Furthermore, in our series IFP of the stomach share common features. In contrast to intestinal IFP, gastric tumours occur at higher age, show heavy inflammation and tend to be smaller. IFP located in the small intestine are frequently associated with intussusception.

CONCLUSION

We conclude that there is a 'small bowel' and a 'gastric' phenotype of IFPs which are associated with exon 12 and exon 18 PDGFRA mutations, respectively.

Gastrointestinal stromal tumor: advances in diagnosis and management

CONTEXT

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract and should be differentiated from other mesenchymal tumors. They harbor specific activating mutations in the KIT or platelet-derived growth factor receptor α ( PDGFRA ) receptor tyrosine kinases, which makes them responsive to pharmacologic inhibitors, such as imatinib mesylate and sunitinib malate.

OBJECTIVES

To provide a comprehensive review of the pathogenesis of GIST and the underlying principles of targeted therapy, to review the salient histologic and immunohistochemical features that facilitate the distinction of GIST from other mesenchymal neoplasms of the gastrointestinal tract, and to present the prognostic parameters for risk stratification that guide clinical management.

DATA SOURCES

Review of the English literature through PubMed as well as personal experience. Photographs were taken from cases encountered at the Cleveland Clinic.

CONCLUSIONS

The discovery of the KIT -GIST connection has not only improved the diagnostic accuracy of GISTs but also provided us with a better understanding of the histogenesis and molecular pathogenesis of these neoplasms.

Benign gastrointestinal mesenchymal BUMPS: a brief review of some spindle cell polyps with published names

CONTEXT

There are several benign, predominantly spindle cell, mesenchymal proliferations involving the mucosa and/or submucosa in the gut, which present as polyps and pathologists see as polypectomy specimens. These include perineuriomas, Schwann cell nodules, ganglioneuromas, leiomyomas of the muscularis mucosae, inflammatory fibroid polyps, and granular cell tumors.

OBJECTIVES

To evaluate these mesenchymal polyps for their morphologic, immunohistochemical, ultrastructural, and molecular characteristics and to determine some of their associations.

DATA SOURCES

Personal observations based on years of analyzing endoscopic biopsies and a review of the world's literature.

CONCLUSIONS

These polyps do surface every so often. There is significant literature covering inflammatory fibroid polyps and granular cell tumors, but there is little literature about the other entities.

Gastrointestinal Tract Mesenchymal Lesions

This article reviews the most common and characteristic mesenchymal lesions found in the gastrointestinal tract and intraabdominal location in a pattern-based approach: spindle and epithelioid tumors (gastrointestinal stromal tumor, schwannoma, glomus tumor, leiomyoma and leiomyosarcoma, inflammatory fibroid polyp, perineurioma, melanoma, calcifying fibrous tumor, sclerosing mesenteritis, mesenteric fibromatosis, and inflammatory myofibroblastic tumor), and clear and granular tumors (clear cell sarcoma, granular cell tumor, gangliocytic paraganglioma, and ganglioneuroma). Information includes gross and histologic features, diagnosis and differential diagnosis, and histologic and other diagnostic techniques, including immunohistochemistry related to projected patient outcome, along with prognosis, staging, and treatment.

Gastrointestinal stromal tumours--an update for histopathologists

This review aims to summarize recent knowledge gained about gastrointestinal stromal tumour (GIST) of particular relevance to histopathologists. KIT and PDGFRA mutation analyses can be useful for confirming a diagnosis of GIST, but there are some diagnostic limitations to these analyses, and so immunohistochemical markers currently remain crucial to the diagnostic process. Of these markers, CD117 and Discovered on GIST 1 (DOG1) are currently the most sensitive and specific markers of GIST, and recent data appear to disprove the fear that antigen retrieval causes false-positive CD117 immunostaining. The accurate prognostication of GIST has been greatly helped by the National Institutes of Health (NIH) and Armed Forces Institute of Pathology (AFIP) classification systems, although both systems still have limitations, and the behaviours of certain GIST subgroups are less well predicted by both systems. KIT and PDGFRA mutation analyses can help to predict the response of GISTs to receptor tyrosine kinase inhibitors, and both GISTs that respond and those that show resistance to these inhibitors may show characteristic pathological changes. Some GIST subgroups (e.g. Carney syndrome and paediatric GISTs) have had recently described clinicopathological and/or molecular characteristics which may help with the diagnosis and/or treatment of these specific neoplasms.

Gastrointestinal Mesenchymal Neoplasms other than Gastrointestinal Stromal Tumors: Focusing on Their Molecular Aspects

Gastrointestinal (GI) mesenchymal tumors other than gastrointestinal stromal tumor (GIST) are rare neoplasms, but they often enter the differential diagnosis of more common GI lesions. Some of these mesenchymal tumors in the GI tract have well understood molecular pathologic aspects, including desmoid tumors, inflammatory myofibroblastic tumor (IMT), clear cell sarcoma (CCS), inflammatory fibroid polyp (IFP), and synovial sarcoma (SS). Molecular pathology is fast becoming a mainstream focus in laboratories because it aids in the precise classification of tumors, may be prognostic, and may help predict response to therapy. The following review is not intended as an exhaustive summary of all mesenchymal tumors that have been reported to involve the GI tract, but instead will highlight the current knowledge of the most important non-GIST GI mesenchymal neoplasms, focusing on those tumors with well-characterized molecular pathology and how the molecular pathologic features impact current diagnostic, therapeutic, and prognostic standards.

[Inflammatory fibroid polyp: from Vanek's "submucosal granuloma" to the concept of submucosal mesenchymal neoplasia]

Inflammatory fibroid polyps (IFP) were described by Vanek 60 years ago as "submucosal granuloma with eosinophilic infiltration". IFP represent polypous proliferations of spindle cells in the submucosa and mucosa of the stomach, small bowel and colon with inflammatory infiltration. The lesions have been regarded as inflammatory and reactive. Recent data show that the spindle cells express PDGFRA, and the majority of IFP harbour activating PDGFRA mutations. Therefore, IFP represent true benign mesenchymal tumors of the gastrointestinal tract.

Comparison of morphological, immunohistochemical, and molecular genetic features of inflammatory fibroid polyps (Vanek's tumors)

Vanek's tumor (inflammatory fibroid polyp) is a rare benign lesion occurring throughout the digestive tract. Histologically, two patterns can be recognized. Classical Vanek's tumor contains concentric formations of proliferating spindle cells which are CD34 positive. Atypical, inflammatory pseudotumor-like Vanek's tumor lacks concentric formations and is CD34 negative. Recently, mutations in platelet-derived growth factor receptor alpha (PDGFRA) were reported in gastric and small intestinal Vanek's tumors. In this study, KIT exons 9, 11, 13, and 17, PDGFRA exons 12, 14, and 18, and a part of exon 15 BRAF for point mutation V600E were screened in 23 cases of Vanek's tumor, both classical (n = 16) and inflammatory pseudotumor-like (n = 7). No mutations in all analyzed exons of KIT and BRAF and in exon 14 of PDGFRA were detected. Six Vanek's tumors harbored activating mutations in PDGFRA exons 12 (n = 5) and 18 (n = 1) respectively: S566_E571delinsK (n = 1), S566_E571delinsR (n = 4), and D842 del (n = 1). The mutations were detected in the classical (n = 5), as well as inflammatory pseudotumor-like (n = 1) Vanek's tumors. The results of this study suggest that the two morphological patterns of Vanek's tumor more probably represent only variants of one type of tumor than two different lesions. Furthermore, BRAF mutations were not shown to drive growth of PDGFRA wild-type Vanek's tumors.