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

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.

Endoscopic submucosal dissection for the treatment of a large inflammatory fibroid polyp in the gastric antrum prolapsing into the duodenum: A case report

RATIONALE

Inflammatory fibroid polyp (IFP), also known as Vanek tumor, is a rare, benign gastrointestinal lesion characterized by its inflammatory and fibroid histological features. IFP is often discovered incidentally during endoscopic examinations. It is exceedingly rare for an IFP to prolapse into the duodenum and results in incomplete obstruction of the pylorus.

PATIENT CONCERNS

A 64-year-old male patient was admitted to the hospital with recurrent episodes of melena over a 6-month period, along with complaints of dizziness and fatigue in the past 10 days.

DIAGNOSES

Gastroscopy showed a giant polypoid mass on the posterior wall of the gastric antrum, prolapsing into the duodenum. Abdominal computer tomography (CT) confirmed the tumor protruding into the duodenum. Pathologic examination of the resected specimen confirmed the IFP diagnosis.

INTERVENTIONS

The giant tumor was completely and successfully excised using endoscopic submucosal dissection (ESD). After the surgery, the patient underwent acid suppression and fluid replenishment therapy.

OUTCOMES

The patient responded well to ESD and was discharged in stable condition. As of the submission of the case report, there has been no recurrence of the tumor after a 5-month follow-up, and the patient is still under follow-up.

LESSONS

While IFPs have traditionally been managed surgically, ESD demonstrates promising treatment outcomes, avoiding the need for surgical distal gastrectomy, and emerges as a safe and effective treatment option.

Incidental findings in the bowel cancer population screening program: other polyps and malignancies - A nationwide study

The introduction of bowel cancer population screening programs has had a profound impact on gastrointestinal pathology. While the focus is mainly on quality assurance of diagnoses relevant for the outcome of these programs (colorectal cancer and its precursors), incidental findings are increasingly diagnosed. The incidence of such findings is largely unknown. Therefore, we investigated the incidence of incidental findings within the national screening program of the Netherlands. From the Dutch nationwide pathology databank (PALGA), we retrieved all histological diagnoses of patients participating in the national bowel cancer screening program from the start in 2014 until 1/1/2021. Descriptive statistics were used. During these 7 years, in total 9407 other polyps and malignancies (262 per 10,000 colonoscopies) were diagnosed. The majority (65%) were classified as inflammatory polyps. The most common malignancies were neuroendocrine tumours (n = 198, 6 per 10,000 colonoscopies); less common were lymphomas (n = 64) and metastases (n = 33). Mesenchymal polyps, such as leiomyomas and lipomas, were relatively common (27 and 16 per 10,000 colonoscopies, respectively), in comparison with neural polyps such as perineuriomas, ganglioneuromas, and neurofibromas (respectively 3, 2, and 1 per 10,000 colonoscopies). This is the largest study into the incidence of nonconventional colorectal polyps and malignancies in a homogeneous cohort of asymptomatic patients. Several of these diagnoses may have consequences for treatment and follow-up, in particular the malignancies and detection of patients with hereditary cancer syndromes.

Case Report: Ileo-Ileal Intussusception Secondary to Inflammatory Fibroid Polyp: A Rare Cause of Intestinal Obstruction

Introduction

Intussusception is a telescoping of a bowel segment into another and it can be a surgical urgency. Most adult intussusceptions arise from a lead point which can be benign or malignant. For this reason, intussusception in adults should undergo surgery. Here we describe a case of ileal inflammatory fibroid polyp (IFP), presenting with ileo-ileal intussusception and obstruction.

Case report

A 54-year-old Caucasian woman presented for acute abdominal pain. A radiography and a CT of the abdomen were performed, which showed signs of occlusion due to an ileo-ileal intussusception. An urgent laparoscopy was performed, the intussusception was extracorporeally reduced, the ileal segment involved was resected, and an ileo-ileal anastomosis was performed. The intussusception seemed to be caused by a 3-cm intra-mural lesion.

Discussion

Intussusception is a surgical concern. While most cases are idiopathic in children, 90% of adult intussusceptions are caused by underlying diseases. Therefore, intussusception in adults should undergo surgery. Radiology is necessary for the diagnosis: the CT scan helps localizing the lesion and shows pathognomonic signs. This case report analyzes an intussusception caused by an inflammatory fibroid polyp. Accurate diagnosis of IFP is only possible with histopathological examination, helped by immunohistochemistry. The differential diagnosis is important because some lesions are malignant.

Conclusion

We reported a case of intussusception caused by an IFP. The diagnosis was made with a CT scan together with intraoperative findings and histopathological examination, which excluded potential differential diagnoses. The patient underwent an explorative laparoscopy, with an ileal resection and anastomosis. Due to the risk of malignancy, surgery is mandatory.

NF1-Associated Inflammatory Polyp of the Colon: First Report of a Sporadic Case

"Juvenile-like (hyperplastic/inflammatory) mucosal polyp" is a term proposed for rare benign mesenchymal lesions of the gastro-intestinal tract so far reported only in patients with type 1 neurofibromatosis (NF1). We report here a first sporadic case of NF1-associated mucosal inflammatory polyp of the colon. The diagnosis was made in a 53-year old female patient with a large polypoid tumor of the cecum. The lesion was predominantly mucosal, made of fibroblast-like cells associated with inflammatory infiltrates rich in eosinophils and containing entrapped, distorted epithelial glands, responsible for the juvenile-like appearance. Whole exome sequencing showed a pathogenic variant of NF1. The patient had no evidence of NF1; no NF1 mutation was detected in normal tissues. Our observation may support the existence of juvenile-like inflammatory polyps associated with NF1 alterations, either germline or somatic. This justifies to test NF1 in difficult-to-classify gastrointestinal mesenchymal tumors.

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.

Endoscopic mucosal resection of a large inflammatory fibroid polyp (Vanek's tumor): a case report

Vanek’s Tumor (inflammatory fibroid polyp) is a rare benign mesenchymal lesion occurring throughout the digestive tract. Classical Vanek’s tumor (“gastric”) contains concentric formations of proliferating spindle cells, which are CD34 positive. Atypical-inflammatory pseudotumor-like Vanek’s tumor (“intestinal”) lacks concentric formations and is CD34 negative. A 70-years-old man patient presented during hematochemical routine tests, sideropenic anemia and leukopiastrinosis. The patient performed osteomyelitis biopsy and esophagogastroduodenoscopy (EGD) showing a gastric wall with nodular appearance and, in antrum pre-pyloric, a polypoid pedunculated lesion, measuring approximately 3 cm in diameter, surrounded by hyperemic mucosa. The lesion then was removed by en bloc endoscopic mucosal resection (EMR) and histo-morphological, immune-cytochemical and biomolecular evaluations were performed. The data were compatible with a benign polyp fibroid inflammatory (Vanek’s Tumor). The results of this study suggest that endoscopic mucosal resection is a safe and efficacy solution for the resection of these gastrointestinal polyps and the two morphological patterns of Vanek’s tumor more probably represent only variants of one type of tumor than two different lesions. BRAF mutations were not shown growth PDGFRA wild-type Vanek’s tumor. (www.actabiomedica.it)

Ileal Intussusception in an Adult Caused by a Locally Invasive Inflammatory Fibroid Polyp: A Case Report

Inflammatory fibroid polyps (IFPs) are rare mesenchymal neoplasms affecting the gastrointestinal tract which are considered benign and noninvasive. We present a case of an invasive IFP in a 46-year-old woman who presented with signs of intestinal obstruction due to ileal intussusception. A segment of the small intestine was resected and subsequently intestinal continuity was restored. A polypoid lesion was found obstructing the lumen. Histopathology revealed a mesenchymal proliferation of spindle and stellate cells, without cytological atypia, arranged in a fibromyxoid stroma. The tumor cells were located in the submucosa but also infiltrated the muscularis propria and the subserosa and were CD34 positive. The molecular study by PCR showed mutation in exon 12 of the PDGFRA gene. IFP is considered a true neoplasm and can also be considered as a potentially invasive lesion.

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.

Sclerosing Tumors of the Gastrointestinal Tract: A Systematic Approach

Some lesions in the gastrointestinal tract have a propensity for sclerosis such that it may mask the actual true nature of the lesion. The purpose of this review is to highlight those lesions of the gastrointestinal tract that can be attended by sclerosis. The sclerosis can mask the cellularity of the lesion; hence, knowledge of the key lesions that are known to have sclerosis will be aid the diagnostic pathologist.

Vanek's tumor as an unusual cause of ileo-ileal intessuception - A unique case report

BACKGROUND AND AIM

Vanek's tumor is a rare solitary lesion that is non-neoplastic, and arises from the submucosa of the gut. The most commonly affected sites are the stomach and the ileum [1]. IFP causing intestinal obstruction is uncommon and that ileo-ileal intussusception has been reported in the literature rarely. We present a case of an ileo-ileal intessuception in a patient who presented with acute on chronic pain abdomen and anorexia. CT abdomen & pelvis revealed a 46 × 36 mm intraluminal mass in the left iliac fossa causing ileo-ileal intussusception.

CASE PRESENTATION

A 60 years old gentleman was brought to the A&E with a history of intestinal obstruction. He was examined and admitted to the surgical unit. CBC revealed unique feature of reactive thrombocytosis apart from a low hemoglobin and a raised TLC. His CT scan demonstrated findings of ileo-ileal intussusception. After an informed written consent, patient underwent an exploratory laparotomy and had resection and anastomosis of the bowel. Histopathology of the specimen revealed findings compatible with IFP. Patient made an uneventful recovery post-operatively and was sent home in the next few days. On follow-up, the patient was doing well and had no complaints of abdominal pain or anorexia.

CONCLUSION

Vanek's tumor although a rare entity, should be considered in each case of acute abdomen and physicians and surgeons need to have a high degree of suspicion in such cases. Moreover, IFP can cause reactive thrombocytosis that gets resolved after a post-operative period of 6-8 weeks.

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.

Gastric inflammatory fibroid polyp tumor with acute intestinal obstruction-Vanek's tumor can mimick a giant gastrointestinal stromal tumor or a gastric lymphoma

An inflammatory fibroid polyp (IFP) is a solitary rare benign neoplasm of the gastrointestinal tract, frequently located in the gastric antrum. IFPs account for about 0.1% of all gastric polyps. We report a case of a giant gastric inflammatory polyp of 2.5 cm × 7 cm that determines a gastric outlet obstruction called "ball valve syndrome" mimicking a gastrointestinal stromal tumor (GIST) and a gastric lymphoma, with an intestinal obstruction of high origin. Therefore, due to acute presentation we have decided to submit the patient to a subtotal gastrectomy. The patient was discharged two weeks later, asymptomatic. At 14 months of follow-up, patient is disease free at abdominal CT and OGDS. Depending on their size and location, IFPs can be associated with unspecific symptoms. Giant IFPs of the gastric antrum or the duodenum can determine an intermittent gastric outlet obstruction called "ball valve syndrome". Endoscopic biopsies are unhelpful and right diagnosis can be reached only with resection. In fact, only about 10% of the gastric lesions are diagnosed correctly prior to resection. Surgical treatment with complete resection with safe margins is curative. Giant IFPs are rare benign lesions whose atypical presentation can mimic GISTs, lymphomas or carcinomas. Clinical and radiological findings may not clarify the right diagnosis until histopathological evaluation aided with immunohistochemical analysis. The resection of IFPs with negative margins is curative with a good clinical outcome. In acute presentation, like in our case, surgery is the mainstay of treatment.

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.

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.

Endoscopic diagnosis and treatment of inflammatory fibroid polyps

AIM: To investigate the clinical manifestations, endoscopic and ultrasonographic features, and endoscopic therapy of gastric inflammatory fibroid polyps (IFPs).

METHODS: A total of 13 patients with IFPs treated at our center were collected between January 2007 January and April 2014. The clinical data for these patients were reviewed. All patients underwent digestive endoscopy, and 5 patients whose lesions were located at the antrum underwent endoscopic ultrasonography before therapy. Therapeutic methods were selected based on endoscopic morphology of the lesion.

RESULTS: IFPs had a modest female predominance (8 women and 5 men), with the majority of patients (11) being more than 50 years. Involved sites included the stomach (10), ileum (2), and colon (1). The tumors ranged in size from 6-60 mm (mean, 21.62 mm). Endoscopic features of the 13 lesions were submucosal tumors (7), polyps (3) and neoplasms (3). All lesions were located in the second (2) or third (3) sonographic layer of the antrum without involvement of the fourth layer. Endoscopic ultrasonographic features were hypoechoic/homogeneous echo pattern and unclear boundary. Four patients underwent endoscopic mucosal resection (EMR), 6 underwent endoscopic submucosal dissection (ESD) and 3 partial gastrointestinalresection. All were confirmed histologically as IFPs.

CONCLUSION: IFPs can occur throughout the gastrointestinal tract, commonly in the antrum. Understanding the characteristic digestive endoscopy and EUS features of IFP scan be helpful to IFP diagnosis. Treatmentby EMR or ESD iseffective and safe.

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.

Juvenile-like (inflammatory/hyperplastic) mucosal polyps of the gastrointestinal tract in neurofibromatosis type 1

AIMS

Diffuse neurofibromatosis/ganglioneuromatosis, solitary/plexiform neurofibroma, periampullary carcinoids and gastrointestinal stromal tumour (GIST) are the main gastrointestinal manifestations of neurofibromatosis type 1 (NF-1, von Recklinghausen disease). Inflammatory (juvenile-like) polyps have not been recognised to date as specific gastrointestinal (GI) manifestations of NF-1.

METHODS AND RESULTS

We describe four males aged 23-65 years with NF-1 and inflammatory (juvenile-like) gastrointestinal polyps, and review the literature for similar cases. Two patients had single polyps (sigmoid colon and antrum, respectively), one had two polyps (left colon), and one had three polyps (distal oesophagus and colon). Histological appearances were variable, ranging from juvenile-like to granulation tissue-rich, predominantly inflammatory and hyperplastic. Three lesions showed obliterative vasculopathic changes. None had neurofibromatous or ganglioneuromatous polyps. A review of the literature disclosed 11 similar cases. Most patients presented with severe gastrointestinal symptoms and/or anaemia.

CONCLUSIONS

NF-1-associated inflammatory polyps probably represent specific GI manifestations of this disorder, and should be considered, particularly in patients with GI symptoms. They should be distinguished from inflammatory fibroid polyps and from juvenile-like changes associated with ganglioneuroma/ganglioneuromatosis and neurofibroma/neurofibromatosis. Their aetiology remains obscure, but different mechanisms, including NF-1 inactivation, NF-1-associated vasculopathy, and localised mucosal prolapse/damage caused by motility disorders, might be involved.

Inflammatory fibroid polyps of the gastrointestinal tract: spectrum of clinical, morphologic, and immunohistochemistry features

Inflammatory fibroid polyps (IFPs) are rare, benign tumors that can arise throughout the gastrointestinal tract. Although the molecular pathogenesis of these lesions has been well characterized, their morphologic features often vary. We report the clinicopathologic findings of the largest series of IFPs to date. A total of 83 IFPs seen at our institution were collected between 1999 and 2012. The specimens included 64 biopsies and 19 resections. A review of the clinical features identified a modest female predominance (47 women and 36 men) with patients ranging in age from 26 to 87 years (mean, 60 y). Involved sites included the esophagus (n=2), stomach (n=31; mainly antrum), small intestines (n=17), appendix (n=1), large intestines (n=31; majority within the rectosigmoid), and anal canal (n=1). Although most patients had a nonspecific presentation, those with small intestinal lesions frequently presented with intussusception. Grossly, the tumors ranged in size from 0.2 to 4.2 cm (mean, 1.7 cm). Histologically, IFPs were centered within the submucosa in all resection specimens, but mucosal extension was found in 74 of 83 (89%) cases. The tumors varied in both cellularity and degree of vascularity. However, the characteristic feature of perivascular onion skinning was present in only 54% (45/83) of the cases. In addition, a short fascicular growth pattern was also noted in 36% (30 of 83) of cases, whereas both features were present in 14 cases (17%). Eosinophils were present in 94% (78 of 83) of cases but varied widely in number from abundant (20/hpf) to sparse (1/hpf). Interestingly, in those cases with sparse eosinophils, prominent hyalinization was also present (11 of 78, 13%). In addition, although the majority of IFPs expressed CD34, 6 of 44 (14%) were negative. No associated dysplasia or malignancy was seen. IFPs represent a diverse set of submucosal-based lesions that commonly extend into the mucosa, making them amenable to endoscopic biopsy. Although their classic histologic features of perivascular onion skinning and predominance of eosinophils are well described, they may alternatively present with a short fascicular growth pattern, a sparse number of eosinophils, and prominent hyalinization.

Inflammatory fibroid polyp of rectum mimicking rectal cancer

Inflammatory fibroid polyps (IFPs) are rare benign tumors of the rectum. Mutation and activating platelet-derived growth factor receptor alpha (PDGFRA) contribute to tumor development. We present a case of IFPs in the middle rectum that mimic rectal cancer. A 65-year-old woman presented with the symptom of fresh blood in the stool and body weight loss of 6 kg in the preceding 3 weeks. A rectal polypoid tumor was noted upon digital examination. Sigmoidoscopy showed a middle rectal tumor measuring 3 × 2.7 cm with obstruction. Computed tomography (CT) scans of the abdomen showed a rectal tumor that had invaded the sacral bone and was associated with four enlarged lymph nodes greater than 1 cm. The radiological report suggested a diagnosis of rectal cancer with lymph node metastases. To remove the obstruction, the patient was initially treated with excision of the tumor and loop sigmoidal colostomy to the abdomen wall. Total mesorectal resection of rectal and sacral tumor followed 10 days later. Histopathological examination of the rectal and sacral tumor showed proliferation of vessels, fibroblast-like spindle cells, and mixed inflammatory cells, including the plasma cells and eosinophils. The spindle cells were diffusely positive to PDGFRA and were focal positive to CD34 and smooth muscle actin. Based on histopathological and immunohistochemical findings, the diagnosis of IFP is indicated. This was the first reported case of IFPs of the rectum presenting with lymph node enlargement and attachment to the sacrum mimicking rectal cancer.

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.

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 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.

Benign serrated colorectal fibroblastic polyps/intramucosal perineuriomas are true mixed epithelial-stromal polyps (hybrid hyperplastic polyp/mucosal perineurioma) with frequent BRAF mutations

Colorectal fibroblastic polyp and intramucosal perineurioma are 2 synonyms for a recently described benign mucosal lesion with a predilection for the rectosigmoid colon. These lesions are characterized by aggregates of bland spindled cells separating and distorting mucosal crypts. The latter frequently showed a serrated architecture. The pathogenesis of fibroblastic polyp/intramucosal perineurioma and the nature of serrated crypts observed in them are poorly understood. We analyzed the clinicopathological features of 29 fibroblastic polyps and investigated them for the first time for mutations known to be involved in serrated colorectal epithelial polyps (BRAF, KRAS, and PIK3CA). Patients were 23 women and 6 men with a mean age of 64 years (range: 47 to 84 y). All lesions represented asymptomatic solitary polyps (mean size 3.5 mm) localized predominantly in the rectosigmoid colon (81%). Hyperplastic polyps, classical adenoma, and sessile serrated adenoma/lesion coexisted in 12 (44%), 12 (44%), and 5 (17%) patients, respectively. All lesions showed irregular aggregates of bland spindled cells separating and distorting mucosal crypts. Serrated (hyperplastic) crypts were observed on the top or contiguous with the lesion in all cases. Immunohistochemistry revealed expression of at least one perineurial cell marker (epithelial membrane antigen, claudin-1, and glucose transporter-1) in 26 out of 27 lesions (96%), but expression of CD34 was less common (8 of 27; 30%). Immunostaining for hMLH1 showed a normal nuclear expression. Molecular analysis in 22 cases showed V600E BRAF mutation in 14 cases (63%) and KRAS mutation in 1 (4%). The remainder were wild-type for all 3 genes. Our results indicate that serrated fibroblastic polyps/intramucosal perineuriomas represent a unique type of mixed epithelial-stromal polyps (hybrid hyperplastic polyp/mucosal perineurioma). The perineurial stromal component might be derived from modified pericryptic fibroblasts as a consequence of a yet poorly understood epithelial-stromal interaction.

Paroxysmal spontaneous nystagmus and vertigo evoked by lateral eye position

Prolonged lateral eye position to the extreme left for 5 to 20 seconds, without vestibular stimulation, induced intense attacks of nystagmus and rotational vertigo lasting 50-90 seconds in a patient. During the attacks the nystagmus beat to the right and counterclockwise, while the patient could look freely around. Clinical data were suggestive of repeated strokes in the vertebrobasilar territory, mainly affecting the right dorsolateral medulla oblongata including the vestibular nuclei. A paroxysmal attack of nystagmus and vertigo evoked by voluntary lateral eye position is an unusual clinical finding. This is discussed in the light of multisensory integration within the vestibular system, which also includes eye position information.