Gastrointestinal stromal tumor versus intra-abdominal fibromatosis of the bowel wall: a clinically important differential diagnosis

Case report: Desmoid fibromatosis diagnosed in a 27-year-old male after being mistaken for a gastrointestinal stromal tumour

Despite being distinct lesions, gastrointestinal stromal tumours (GISTs) and desmoid fibromatosis may appear similar on imaging when they involve the stomach wall or bowel. As a result, they may be confused with one another when initially diagnosed. This report aims to present a case where a desmoid tumour was mistaken for a gastric GIST in a 27-year-old gentleman despite extensive investigation prior to exploratory laparotomy, and why differentiation through pathology, with a focus on the immunohistochemistry profile, is key for proper prognostication and appropriate management, including timely investigation for associated diseases such as Familial Adenomatous Polyposis in patients with desmoid tumours.

Gas-containing mesenteric desmoid-type fibromatosis: A case report

RATIONALE

Desmoid-type fibromatosis is a rare benign mesenchymal neoplasm. Only 8% of desmoid-type fibromatosis develops in the abdominal cavity. The mesentery is seldom affected and gastrointestinal stromal tumors need to be considered in the differential diagnosis, particularly when imaging examination shows a tumor containing gases in the abdominal cavity. Only a few cases of gas-containing mesenteric desmoid-type fibromatosis have been reported in the literature.

PATIENT CONCERNS

A 69-year-old male patient presented with hematochezia and intermittent upper abdominal pain.

DIAGNOSIS

Contrast-enhanced computed tomography revealed a 3.9 × 3.6 cm gas-containing mass infiltrating the third portion of the duodenum. The tumor was heterogeneous, with cysts and air bubbles. It showed heterogeneous weak-to-mild enhancement in the solid part. Postoperative pathological examination confirmed a final diagnosis of mesenteric desmoid-type fibromatosis.

INTERVENTIONS

The patient underwent surgical resection of intra-abdominal lesion.

OUTCOMES

No evidence of local recurrence was noted during the 6 months of follow-up.

LESSONS

Accurate preoperative diagnosis is difficult for an intra-abdominal gas-containing mass on computed tomography scan. The appearance of spiculated infiltrative margin suggests the diagnosis of desmoid-type fibromatosis. Further investigation of imaging evidence and treatment methods is necessary.

Invasive giant pancreatic desmoid-type fibromatosis with curative resection: A case report

Introduction

Desmoid-type Fibromatoses (DTF) tumours are rare, benign fibrous tumours with aggressive invasive behaviour that account for approximately 0.03% of all neoplasms. We report the success in curing a rare, invasive, and huge pancreatic intraabdominal DTF.

Presentation of case

A 42 years old male was medically free apart from recurrent left upper abdominal pain, anorexia, and nausea for more than ten years and no significant past surgeries, trauma, or family history of cancer. The patient has a non-tender large abdominal mass at the left hypochondria area extending down to the pelvis below the umbilicus with a rigid and smooth surface. The computed tomography scan showed a huge heterogeneous mass appears to be of pancreatic origin, measuring about 23 cm by 15 cm by 11 cm. The patient underwent radical antegrade modular pancreato-splenectomy, segmental transverse colectomy, adrenalectomy, and subsequent colo-colic anastomosis. The accurate gross size of the tumour specimen was 26 × 17 × 9 cm, and the weight was found to be 3.6 kg. Immunohistochemistry confirmed the diagnosis of pancreas DTF. The follow up to 5 years confirmed no recurrence reported clinically or by imaging.

Discussion

The Pancreas origin of DTF is a rarely reported subset with an incidence of around 5% of all DTF. Establishing the diagnosis is fundamentally based on the characteristic pathological and immunohistochemical studies, for the only available cure modality by complete radical resection to be promptly offered.

Conclusion

Our case is rare and uniquely the largest pancreatic DTF reported in the literature with curative resection despite being locally invasive.

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Desmoid-type Fibromatoses (DTF) tumours are rare, benign fibrous tumours with aggressive invasive behaviour.

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Account for approximately 0.03% of all neoplasms.

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The Pancreas is a rarely reported subset with an incidence of around 5% of all DTF.

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Accurate diagnosis is fundamentally by characteristic pathological and immunohistochemical studies.

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Cure can be achieved only by complete radical resection

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We report curative resection of a rare and the largest pancreatic locally invasive DTF (26x17x9 cm in size and weight 3.6Kg)

Desmoid-type fibromatosis difficult to distinguish from GIST : A case report

Background : Desmoid-type fibromatosis is a very rare disease that has no characteristic image findings, so it is often difficult to differentiate from gastrointestinal stromal tumor (GIST). A case of desmoid-type fibromatosis that was difficult to differentiate from GIST is reported. The decisive factor in the diagnosis was positive nuclear immunostaining for β-catenin nucleus. Case presentation : A man is his 30s had no significant past medical history, including no abdominal surgery. A medical check-up found a large tumor in the right lateral abdomen. After some examinations, a preoperative diagnosis of GIST was made, and open ileocecal resection was performed. However, the final diagnosis based on the pathological findings was desmoid-type fibromatosis. Conclusions : We should consider desmoid-type fibromatosis when we find a large abdominal mass, but it may be difficult to diagnose based only on imaging findings. Immunohistochemical examination of the specimen may make the diagnosis. J. Med. Invest. 67 : 375-377, August, 2020.

Huge mesenteric fibromatosis presenting with intestinal perforation and acute diffuse peritonitis: a case report

Mesenteric fibromatosis is a locally invasive myofibroblastic proliferation and rarely metastasize to other organs. Hollow organ perforation and acute diffuse peritonitis caused by mesenteric fibromatosis rarely occurred. Here we report a case of huge mesenteric fibromatosis who complained a paroxysmal epigastric pain, and CT scan showed a huge mass, pneumoperitoneum and ascites. An urgent laparotomy showed an intro-abdominal mass and perforation locating at the jejunum. Postoperative histology confirmed it to be mesenteric fibromatosis. With one-year follow-up, the patient had no recurrence. We wish to share our treating experience of this interesting case because it did not belong to a typical type but presenting with acute diffuse peritonitis, and total resection and R0 margin is a key to treat acute case. This atypical one has not been reported in the literature till now.

Rare acute abdominal condition caused by mesenteric fibromatosis perforation: A case report

RATIONALE

Mesenteric fibromatosis is a rare benign neoplasm with a tendency to spread and recur locally, without metastasis. It may present with a wide spectrum of clinical features; however, onset as a perforation is extremely rare.

PATIENT CONCERNS

The present patient was an 18-year-old female with a 10-hour history of increasing abdominal pain that arose suddenly with nausea and vomiting. She had experienced an appendectomy 2 years before this admission.

DIAGNOSES

A gastrointestinal perforation was initially suspected on the basis of complaints and physical examination. The patient was thoroughly investigated for further diagnosis. Computed tomography showed a large well-defined intra-abdominal mass measuring 7.1 × 6.7 × 5.9 cm in the right lower quadrant, with adjacent small intestine compression and free intraperitoneal air. Then, the patient underwent a laparotomy. Finally, postoperative pathology and immunohistochemistry confirmed mesenteric fibromatosis, with a consecutive perforation from ileum to the bottom of tumor.

INTERVENTIONS

The patient has been treated by a resection of the mass with the adhesive small intestine, without chemotherapy or radiotherapy postoperatively.

OUTCOMES

The patient had an uneventful postoperative recovery. Three months after surgery, the patient reviewed the colonoscopy, no intestinal polyps were noted. The present case has been followed up for 17 months without tumor recurrence.

LESSONS

Our case illustrates another possible cause of acute abdominal pain. Although rare, treating physicians should maintain a high suspicion index while managing a patient with an abdominal mass and pain. Close follow-up is essential because of the high incidence of local tumor recurrence.

Mesenteric fibromatosis in a patient with a history of neuroblastoma: a case report

Mesenteric fibromatosis (MF) is a locally aggressive proliferative spindle cell lesion of the mesentery. A 34-year-old male presented with increasing abdominal pain and constipation. On workup, patient was found to have a large pelvic mass on CT A/P concerning for cancer. The patient underwent surgical excision of >15 cm intra-abdominal tumor along with adherent small bowel section. Histology of the tumor showed a spindle cell lesion consistent with MF. Previous reports have shown association of MF with Gardner syndrome and familial adenomatous polyposis. We present the first reported case of MF in a patient with previous neuroblastoma.

Chest Wall Fibromatosis with Congenital Muscular Torticollis: Two Forms of Deep Fibromatosis in a Child

Desmoid tumors (fibromatosis) are intermediate grade, locally aggressive soft-tissue tumors. A rare case of chest wall fibromatosis in a girl with congenital muscular torticollis is being reported. This report also highlights the need for long-term surveillance in such cases, despite being a benign pathology.

Subsequent Development of Desmoid Tumor after a Resected Gastrointestinal Stromal Tumor

Desmoid tumors (deep fibromatosis) of the mesentery are rare mesenchymal tumors. They are often misdiagnosed, especially with a previous history of resection for gastrointestinal stromal tumor (GIST). Immunohistochemistry can help differentiate between these two tumors. In this article, we present a case we had encountered: a Desmoid tumor developing in a patient with a history of GIST 3 years ago. It is the first case of GIST with subsequent development of Desmoid tumor to be reported in Saudi Arabia. We discuss the two entities of Desmoid tumor and GIST by comparing their definitions, clinical presentations, histological features, immunohistochemistry stains, molecular pathogenesis, prognosis, and treatment. We also discuss the relationship between GIST and the subsequent development of Desmoid tumors and compare our case with case reports in literature.

Multivisceral transplant is a viable treatment option for patients with non-resectable intra-abdominal fibromatosis

BACKGROUND

Intra-abdominal fibromatosis often involves the mesentery root which is non-resectable by conventional surgery. Multivisceral transplant (MVT), as a potential cure to non-resectable fibromatosis, has rarely been reported and the prognosis is unknown.

METHODS

Six patients who underwent MVT for intra-abdominal fibromatosis were reviewed. Clinicopathological features, immunohistochemistry for β-catenin, p53, and Ki67, and outcomes were evaluated. Appropriate data for comparative analysis were obtained from a cohort of 24 patients who underwent conventional resection for intra-abdominal fibromatosis.

RESULTS

Among six MVT patients, four had familial adenomatous polyposis (FAP). Two patients had an initial intestinal transplantation, three had multiple prior surgeries, and two had adjuvant therapy. One patient died of hemorrhagic stroke shortly after MVT, and five patients (83%) survived with a median follow-up of 64 months. The 1-year and 5-year survival rates were 67% for all five patients. Two patients had recurrences after MVT and one of them had FAP. In comparison, six of 24 patients who underwent conventional surgery had FAP; six (25%) had recurrences and three had FAP. For FAP patients; the mean recurrence time was 13 months for MVT versus 6 months for conventional surgery. Ki67 proliferative index, β-catenin, and p53 expression did not significantly correlate to recurrence.

CONCLUSIONS

Multivisceral transplant (MVT) is a viable option for patients who have non-resectable intra-abdominal fibromatosis with promising surviving rates, although recurrence still occurs. Surgical margin, Ki67 proliferative index, β-catenin, and p53 expression are not predicative for recurrence of fibromatosis.

Cytologic and Immunohistochemical Evaluation of Low-Grade Spindle Cell Lesions of the Gastrointestinal Tract

Spindle cell lesions of the gastrointestinal tract are relatively uncommon compared with the frequency of their epithelial counterparts. Although gastrointestinal stromal tumors and leiomyomas are the most commonly encountered spindle cell lesions in the stomach and esophagus, respectively, there are other less common diagnostic entities that should be considered for accurate diagnoses as well as appropriate patient treatment and clinical follow-up. Given the morphologic overlap of low-grade spindle cell lesions on cytologic preparations, ancillary studies play a key role in differentiating these lesions from one another.

Subcellular Localization of Immunohistochemical Signals

In the literature, sufficient attention has not been paid to the precise subcellular localization of immunohistochemical signals, the knowledge of which is essential for proper interpretation of immunostains and distinction of genuine staining from biotin-associated or other nonspecific stainings. The subcellular localization of the signals can in fact be easily deduced from the known biologic or ultrastructural characteristics of the antigens. Extracellular antigens obviously are located in the extracellular compartment. Cellular antigens fall into 3 major groups: membranous, nuclear, and cytoplasmic. Membranous antigens include cell adhesion molecules (such as E-cadherin, N-CAM), cell surface/transmembrane receptors and proteins (such as tyrosine kinase receptors, most leukocyte antigens, CD10, CEA), and molecules linking surface molecules to cytoskeleton (such as β-catenin, dystrophin). Nuclear antigens include cell cycle-associated proteins (such as cyclins, p16, Ki-67), nuclear enzymes (such as TdT), transcription factors (such as TTF-1, CDX-2, myogenin, PAX-5), tumor suppressor gene products (such as p53, p63, WT1, Rb), steroid hormone receptors (such as ER, PR), calcium-binding proteins (such as S-100 protein, calretinin), and some viral proteins (such as CMV, herpes). Cytoplasmic antigens can take up a granular pattern due to localization in organelles, granules, or secretory vesicles (such as chromogranin, hormones, lysozyme, HMB-45), fibrillary pattern attributable to the filamentous nature of the molecules (intermediate filaments and microfilaments), or diffuse or patchy pattern due to localization in the cytosol or large vesicles (such as myoglobin, albumin, thyroglobulin). Aberrant localization of the molecules, when present, can provide important insight into disease processes and aid in their diagnosis, such as loss of membranous E-cadherin expression in lobular breast carcinoma, aberrant nuclear localization of β-catenin in colorectal adenocarcinoma, pattern of ALK staining in anaplastic large cell lymphoma correlating with the different types of chromosomal translocations, presence of additional cytoplasmic CD10 staining in the enterocytes indicative of microvillous inclusion disease, and “reversed” staining for EMA in micropapillary mammary carcinoma.

Incidental Finding and Management of Mesenteric Fibromatosis

Patient: Male, 45

Final Diagnosis: Mesenteric fibromatosis

Symptoms: —

Medication: —

Clinical Procedure: Surgical removal of the mesenteric fibromatosis

Specialty: Surgery

Is wide resection obsolete for desmoid tumors in children and adolescents? Evaluation of histological margins, immunohistochemical markers, and review of literature

Desmoid fibromatosis is a benign fibroblastic neoplasm with high recurrence rates predominantly observed in pediatric and adolescent patients. The use of wide resection margins has been discussed controversially in literature. In addition, data on non-surgical treatment is limited as phase III studies are still missing. Nineteen patients under the age of 18 years were identified. Tumor location, surgical treatment for primary or recurrent tumors, resection margins, medical neo-/adjuvant treatment, time to recurrence as well as immunohistochemical markers (estrogen receptor, ER α and β, progesterone and androgen receptors, somatostatin, Ki-67, c-kit, platelet-derived growth factor receptors, PDGFRs, α and β, β-catenin) were evaluated. The mean age at diagnosis was 6.6 years, with a mean follow-up of 114 months. Recurrences were detected in four out of nineteen patients. Surprisingly, the recurrence rate was not influenced by type of resection used (R0, R1/2). All samples were tested negative for ER α, somatostatin, and progesterone receptor. In contrast, a majority of tumors showed positive results for PDGFR α and β and β-catenin. No correlation between positive immunohistochemical markers and tumor recurrences was detectable. In conclusion, recurrence rates are not depending on resection type and immunohistochemical markers seem to behave differently in children and adolescents in contrast to adult patients.

Mesenteric fibromatosis

Mesenteric fibromatosis is a rare, locally invasive, non-metastasizing type of intra-abdominal fibromatoses with a very high rate of recurrence. Because of rarity, these tumors pose a diagnostic and therapeutic challenge. These tumors may remain asymptomatic, but commonly present as a painless mass. There are no clear treatment guidelines. Surgical excision with wide margin is the preferred modality of treatment. Medical therapy is indicated for inoperable and recurrent tumors. There are several isolated case reports on mesenteric fibromatosis with different and unusual presentations and its complications. Though several studies have been published on extra-abdominal fibromatosis as well as on extramesenteric abdominal fibromatosis, but extensive research studies are still lacking on mesenteric fibromatosis. The aim of this article is to present current knowledge on mesenteric fibromatosis, our experience of four cases, and comprehensive review of available literature.

Intra-abdominal desmoid tumor difficult to distinguish from a gastrointestinal stromal tumor: report of two cases

Desmoid tumors are benign fibroblastic neoplasms with no metastatic potential, but a propensity for local recurrence even after complete surgical resection. These lesions can develop at any site in the body, and commonly occur in the intra-abdominal area. Intra-abdominal desmoid tumors usually occur at the mesentery or retroperitoneum, and may morphologically mimic gastrointestinal stromal tumors (GISTs). Distinguishing between these tumors is important, because the therapies differ substantially, but is often difficult even with the use of CD117 staining. We herein report the cases of two patients with sporadic intra-abdominal desmoid tumors that were differentiated from GIST by immunohistological examination using beta-catenin and CD34. Desmoid tumors specifically express nuclear beta-catenin, and show no expression of CD34. We recommend staining for beta-catenin and CD34 when an intra-abdominal desmoid tumor is suspected.

Intra-abdominal fibromatosis: differentiation from gastrointestinal stromal tumour based on biphasic contrast-enhanced CT findings

AIM

To identify the computed tomography (CT) criteria that differentiate intra-abdominal fibromatosis (IAF) from gastrointestinal stromal tumour (GIST).

MATERIALS AND METHODS

CT images of 34 pathologically proven cases of IAF (n = 15) and GIST (n = 19) were retrospectively reviewed. Location, contour, border, enhancement pattern, presence of necrosis, vessels, and air within the lesion were analysed. Long diameter (LD), short diameter (SD), LD/SD ratio, degree of enhancement, and lesion/aorta (L/A) CT attenuation ratio were measured and calculated. Significant CT criteria were identified using Fisher's exact test, grouped t-test, and receiver operating characteristic (ROC) curve. Sensitivity and specificity values were calculated when single or multiple CT criteria were used.

RESULTS

Extra-gastrointestinal location, ovoid or irregular contour, homogeneous enhancement, absence of intra-lesional necrosis, lower degree of enhancement, and L/A CT attenuation ratio differentiated IAF from GIST (p < 0.05). When any three of these eight criteria were combined, the sensitivity and specificity for diagnosing IAF were 100% (15 of 15) and 89.5% (17 of 19), respectively.

CONCLUSION

The following eight CT criteria are helpful to differentiate IAF from GIST: extra-gastrointestinal location, ovoid or irregular contour, homogeneous enhancement, absence of intra-lesional necrosis, a degree of enhancement of less than 40.5 HU in the arterial phase versus 46.5 HU in the portal venous phase, and an L/A CT attenuation ratio <0.315 in the arterial phase versus 0.525 in the portal phase.

Pathology of gastrointestinal stromal tumors

Gastrointestinal stromal tumor (GIST) is a well recognized and relatively well understood soft tissue tumor. Early events in GIST development are activating mutations in KIT or PDGFRA, which occur in most GISTs and encode for mutated tyrosine receptor kinases that are therapeutic targets for tyrosine kinase inhibitors, including imatinib and sunitinib. A small minority of GISTs possessing neither KIT nor PDGFRA mutations may have germline mutations in SDH, suggesting a potential role of SDH in the pathogenesis. Immunohistochemical detection of KIT, and more recently DOG1, has proven to be reliable and useful in the diagnosis of GISTs. Because current and future therapies depend on pathologists, it is important that they recognize KIT-negative GISTs, GISTs in specific clinical contexts, GISTs with unusual morphology, and GISTs after treatment. This review focuses on recent developments in the understanding of the biology, immunohistochemical diagnosis, the role of molecular analysis, and risk assessment of GISTs.

Giant mesenteric fibromatosis: Report of a case and review of the literature

Mesenteric fibromatosis poses a diagnostic and therapeutic challenge. This paper presents a 35-year-old female complaining of vague abdominal pain of 2 mo duration. Her computed tomography scan and magnetic resonance imaging revealed a pelvi-abdominal heterogenous mass with significant displacement of the small bowel and urinary bladder. She underwent surgical excision of the mass with resection and anastomosis of the involved loop of the small intestine. Histological examination confirmed mesenteric fibromatosis without infiltration of the bowel. The patient remained well during the 6 mo follow-up.

Desmoid tumors in the pediatric population

Desmoid tumors are benign soft tissue tumors associated with locally aggressive growth and high rates of morbidity, but they do not metastasize via lymphatic or hematogenous routes. While most of the data on desmoid tumors originates in the adult literature, many of the findings have been applied to the management of pediatric patients. This article discusses the epidemiology, etiology, clinical presentation, pathology, and treatment of this rare tumor in the pediatric population and includes a literature review of the most recent large series of pediatric patients with desmoid tumors.

Desmoid tumour (aggressive fibromatosis) of the colon mimics malignancy on dual time-point 18F-FDG PET/CT imaging

A 58-year-old female who presented with a lower gastrointestinal bleed was referred for an (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT after a colonoscopy revealed a submucosal mass in the ascending colon. The PET/CT confirmed the presence of an FDG-avid mass in the ascending colon with no other FDG-avid abnormalities. Dual time-point imaging was performed and showed a significant increase in FDG uptake in the mass, which raised strong suspicion of a colon malignancy. Although an initial biopsy of the mass did not show evidence of neoplasia, a decision was made to proceed with a right hemicolectomy based on high clinical and imaging suspicion of malignancy. Histological evaluation of the hemicolectomy revealed a benign colon desmoid tumour.

Fibromatosis of the cecum presenting with acute appendicitis: a case report

Although acute appendicitis is a common clinical condition in general surgical practice, <1% of them are associated with malignancies. Appendiceal carcinoids make up most of those malignancies and acute appendicitis cases associated with benign cecal neoplasias are very uncommon. In this study, a 25-year-old female patient who presented with distinct acute appendicitis symptoms is reported. The patient was operated on via open technique. Exploration revealed an appendix with advanced edema and hyperemia. While the cecum was observed to be normal, a solid mass of 2.5 cm diameter was palpated in the appendiceal base. Following the ileocecal resection, histopathological examination revealed the mass as a fibromatosis. The goals of this report are to remind health care professionals that some very rare etiologies may be involved in acute appendicitis diagnosis and treatment, and to underscore the place of laparoscopic approach and preoperative computed tomography in this disease.

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.

Is autophagy rather than apoptosis the regression driver in imatinib-treated gastrointestinal stromal tumors?

Although apoptosis (programmed cell death type I) is more frequently reported in the literature in imatinib-treated gastrointestinal stromal tumor (GIST) cell lines,morphological features consistent with autophagic changes aremore often encountered in surgical specimens of treated patients. Autophagy (programmed cell death type II) is highly regulated by a tumor-suppressor mechanism that mainly involves the genes beclin1, PI3KIII, and bcl2. Being our material not suitable for electron microscopy analysis (not paraformaldehyde-glutaraldehyde-fixed), we evaluated the morphological, biochemical, and immunophenotypical profiles expected to be related to autophagy and apoptosis in a series of surgically resected samples taken from 11 imatinib-treated patients with molecularly characterized GISTs. The samples were examined for imatinib-induced morphological changes, the presence/interactions of the autophagic-related proteins (beclin1, PI3KIII, bcl2, and LC3-II) and the presence of apoptosis-related proteins (caspase 3, caspase 7, and lamin A/C) by means ofWestern blot analysis and coimmunoprecipitation, complemented by immunohistochemistry. We also studied samples of two untreated GISTs used as controls. Sampling areas with different residual cellularity scores fromboth the imatinib-treated and untreated patients showed biochemical and immunohistochemical evidence of high levels of proautophagy beclin1/PI3KIII and low levels of antiautophagy beclin1/bcl2 complexes, together with the presence of LC3-II detected by Western blot analysis, thus supporting the presence of autophagy. There was no expression of cleaved/activated caspase 3 or 7 or cleaved lamin A/C. Our descriptive results support the idea that GISTs activate autophagy rather than apoptosis in response to imatinib treatment and that their molecular makeup includes fingerprints of autophagy.

Fine-needle aspiration diagnosis of GIST: a diagnostic dilemma

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. The authors take this opportunity to report two cases of GISTs of large bowel diagnosed on cytology and confirmed by histopathology and immunohistochemistry.

Colorectal gastrointestinal stromal tumor

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm arising in the digestive tract, with an estimated prevalence of 15-20 per 1,000,000. GISTs are related to the interstitial cells of Cajal and are characterized by constitutive over-expression of the transmembrane tyrosine kinase receptor KIT. This is produced by a patognomonic mutation of the proto-oncogene c-kit that occurs in up to 90% of cases. Exon 11 is affected most frequently; exons 9 and 13 are less commonly involved. One-third of GISTs lacking KIT mutations exhibits alternative activating mutations in the PDGFRα gene. Colorectal GISTs represent about 5-10% of the cases, mainly located in the rectum that is the third common site. Benign GISTs are more common, but many tumors are of uncertain malignant potential; tumor size and rate of mitosis are still the most reliable criteria for assessing the risk of an aggressive behavior. Surgery is the first-line treatment for resectable non-metastatic colorectal GIST. Standard oncologic resection is inappropriate because skip metastases and lymphatic spread are rarely reported. Segmental colectomy with negative margins is recommended, and local excision is oncologically adequate in highly selected rectal tumors. Radical surgery alone is not always curative especially in high-risk GISTs, and half of patients develops local recurrences or distant metastases after R0 operation. Medical therapeutic strategies have rapidly evolved after the introduction of targeted molecular therapy. Efficacy and safety of imatinib mesylate was first demonstrated in patients with metastatic and unresectable disease. Adjuvant and neoadjuvant use of imatinib are promising therapeutic options to improve the outcome of surgery to downstage unresectable lesions and to allow less extensive resections.

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.

Generation of human-induced pluripotent stem cells from gut mesentery-derived cells by ectopic expression of OCT4/SOX2/NANOG

Induced pluripotent stem (iPS) cells have been generated from human somatic cells by ectopic expression of defined transcription factors. Application of this approach in human cells may have enormous potential to generate patient-specific pluripotent stem cells. However, traditional methods of reprogramming in human somatic cells involve the use of oncogenes c-MYC and KLF4, which are not applicable to clinical translation. In the present study, we investigated whether human fetal gut mesentery-derived cells (hGMDCs) could be successfully reprogrammed into induced pluripotent stem (iPS) cells by OCT4, SOX2, and NANOG alone. We used lentiviruses to express OCT4, SOX2, NANOG, in hGMDCs, then generated iPS cells that were identified by morphology, presence of pluripotency markers, global gene expression profile, DNA methylation status, capacity to form embryoid bodies (EBs), and terotoma formation. iPS cells resulting from hGMDCs were similar to human embryonic stem (ES) cells in morphology, proliferation, surface markers, gene expression, and epigenetic status of pluripotent cell-specific genes. Furthermore, these cells were able to differentiate into cell types of all three germ layers both in vitro and in vivo, as shown by EB and teratoma formation assays. DNA fingerprinting showed that the human iPS cells were derived from the donor cells, and are not a result of contamination. Our results provide proof that hGMDCs can be reprogrammed into pluripotent cells by ectopic expression of three factors (OCT4, SOX2, and NANOG) without the use of oncogenes c-MYC and KLF4.

Mesenteric fibromatosis with intestinal involvement mimicking a gastrointestinal stromal tumour

INTRODUCTION

Mesenteric fibromatosis or intra-abdominal desmoid tumour is a rare proliferative disease affecting the mesentery. It is a locally aggressive tumour that lacks metastatic potential, but the local recurrence is common. Mesenteric fibromatosis with the intestinal involvement can be easily confused with other primary gastrointestinal tumours, especially with that of the mesenchymal origin.

CASE REPORT

We report a case of a 44-year-old female who presented with an abdominal mass that radiologically and pathologically mimicked a gastrointestinal stromal tumour.

CONCLUSIONS

The diagnosis of mesenteric fibromatosis should always be considered in the case of mesenchymal tumours apparently originating from the bowel wall that diffusely infiltrate the mesentery.

Surgical treatment of giant mesenteric fibromatosis presenting as a gastrointestinal stromal tumor: a case report

INTRODUCTION

Intra-abdominal fibromatosis, usually located at the mesenteric level, is a locally invasive tumor of fibrous origin, with no ability to metastasize, but a tendency to recur. Certain non-typical cases of intra-abdominal fibromatosis with involvement of the bowel wall can be misdiagnosed because of their different biological behavior.

CASE PRESENTATION

We describe the case of a 64-year-old Caucasian man presenting with mesenteric fibromatosis and involvement of the bowel wall, who was treated surgically. The macroscopic and microscopic appearance of the lesion mimicked a gastrointestinal stromal tumor, a tumor with potential malignant behavior.

CONCLUSION

It is essential to make an early and correct diagnosis in such equivocal cases, so that the appropriate treatment can be chosen and suitable patients admitted to clinical trials if appropriate. New and reliable criteria for discriminating between intra-abdominal fibromatosis and gastrointestinal stromal tumor should be proposed and established because novel sophisticated therapeutic strategies have been introduced in the international literature.

Gastrointestinal Stromal Tumors: A Guide to the Diagnosis

Gastrointestinal stromal tumors (GISTs) have emerged from being a poorly understood and therapeutically refractory sarcoma to a tumor whose biology has not only provided insight into a mechanism of oncogenesis but has also led to a rational basis for therapy. Most GISTs are characterized by KIT protein (CD117) expression and constitutive activating mutations in either the c-kit or platelet-derived growth factor receptor α genes. This information can now be obtained from routine formalin-fixed and paraffin-embedded tissue. Because the correct diagnosis is the key to successful treatment of this tumor, it is incumbent on the pathologist to be familiar with the various gross and histologic patterns shown by these tumors. GISTs range from small incidental stromal nodules to large cystic and solid tumor masses. GISTs show a variety of microscopic patterns and therefore several other tumors enter the differential diagnosis. Fortunately, with an understanding of GIST histology, and with the proper use of immunohistochemistry and molecular analysis, a correct diagnosis can usually be made. In addition to the correct diagnosis, several key attributes of the tumor need to be determined because they provide the basis for proper clinical management. This article summarizes the gross, microscopic, and molecular findings of GISTs, and discusses the differential diagnosis and key attributes of this interesting group of neoplasms.

Simultaneous Colonic Obstruction and Hydroureteronephrosis due to Mesenteric Fibromatosis

Mesenteric fibromatosis (MF) is a rare benign mesenchymal lesion that can occur throughout the gastrointestinal tract, especially small bowel. Its biological behavior is intermediate between benign fibrous tissue proliferation and malignant fibrosarcoma. In previously reported cases of MF, we could find colonic obstruction or ureter obstruction, but simultaneous involvement of colon and ureter was not able to be seen. We described a patient that presented with colonic obstruction and hydroureteronephrosis due to MF at sigmoid colon which mimicked submucosal tumor such as gastrointestinal tumor. This case resulted in a positive positron emission tomography scan suggesting malignant neoplasm, but beta-catenin positivity on immunohistochemical staining separated MF from gastrointestinal stromal tumor and sclerosing mesenteritis. The clinical course of the patient was improved after surgical resection.

Gastrointestinal stromal tumours: a clinico-radiologic review from a single centre in South India

Gastrointestinal stromal tumours (GISTs) are rare tumours but are the commonest mesenchymal neoplasms in the gastrointestinal tract. To our knowledge, there is no large case series in Asian countries in which a clinico-radiological descriptive analysis of these tumours has been carried out. In this retrospective study, we analysed our experience of 70 patients with histopathologically proven GISTs, who were presurgically investigated by using CT, and describe the demography, anatomical distribution, imaging features and clinical course of the GIST. We found an unusually large predominance of males in our study, stomach and small bowel appeared to have been involved similarly and small bowel tumours had a higher rate of metastases. We also highlight some unusual CT features of these tumours that we encountered during the study, such as the presence of metastatic lymphadenopathy and satellite nodules, relapse in appendices epiploicae of the bowel, metachronous liposarcoma, adrenal and lung metastases, multiplicity of lesions and aneurysmal dilatation of the bowel. Two of our patients also had multiple neurofibromas, whose association with GIST has been seen in earlier reports. To the best of our knowledge, this article presents one of the largest series of articles on GISTs, to date, in Asian countries. We conclude with a differential diagnosis of GIST, with salient features distinguishing each entity.

Miscellaneous Pseudotumors and Mesenchymal Tumors of the Female Genital Tract

Benign and malignant soft tissue tumors and pseudotumors can rarely arise anywhere in the female genital tract. Their pathologic features as well as behavior typically overlap with those described in tumors involving typical locations. However, due to their rarity, not infrequently these tumors represent a diagnostic challenge. Their diagnosis should be based on careful gross examination, thorough sampling, and morphologic evaluation, applying a selected immunohistochemical panel and molecular studies. Accurate classification of these tumors is important because their clinical behavior, prognosis, and therapy differ markedly. This article outlines several mesenchymal lesions reported in the female genital tract, encompassing recent histologic, immunohistochemical, and molecular findings, with special emphasis on problems in the differential diagnosis.

Best practices in diagnostic immunohistochemistry: spindle cell neoplasms of the gastrointestinal tract

CONTEXT

The proper classification of spindle cell neoplasms of the gastrointestinal tract frequently requires the use of immunohistochemistry, as the histologic appearance of these lesions often overlaps.

OBJECTIVE

To review the antibodies used in the diagnosis of spindle cell neoplasms of the gastrointestinal tract, and to outline an approach to the evaluation of these lesions by using immunohistochemistry.

DATA SOURCES

The authors' experience and a review of the English literature from 1976 to 2008.

CONCLUSIONS

The most common spindle cell neoplasm of the gastrointestinal tract is gastrointestinal stromal tumor; this lesion is readily diagnosed with c-kit immunohistochemistry in most cases. Other stains, such as smooth muscle actin, desmin, S100 protein, and beta-catenin, are also useful in the diagnosis of smooth muscle tumors, schwannomas, desmoid-type fibromatoses, and metastatic melanoma.

Merkel cell carcinoma: lack of KIT positivity and implications for the use of imatinib mesylate

The large variability (7% to 100%) in previously reported rates of receptor tyrosine kinase KIT expression in Merkel cell carcinoma (MCC) may be owing to the use of heat-induced epitope retrieval. High frequency of reported KIT reactivity by immunohistochemistry (IHC) in part prompted the initiation of a phase 2 clinical trial of imatinib mesylate (Gleevec, Novartis Pharmaceuticals, East Hanover, NJ) for the treatment of advanced MCC. Our experience has been that a small number of MCCs (12.5%) are positive for KIT by IHC. We also found a higher rate of apparently KIT-positive MCCs (75%) using heat-induced epitope retrieval. Our anecdotal experience with the use of imatinib mesylate has been disappointing. As IHC detection of KIT expression does not correlate with the presence of KIT-activating mutations, protein expression as tested by IHC should not be used to determine if patients would respond to imatinib mesylate. Indeed, our review of the literature and the apparent lack of efficacy of imatinib mesylate for MCC in a recent phase 2 trial suggest a minor role for KIT signaling in MCC tumorigenesis.

Histopathological diagnostic discrepancies in soft tissue tumours referred to a specialist centre

Aims. A study was performed to determine areas of diagnostic discrepancy in the reporting of cases of soft tissue tumours referred to a specialist sarcoma unit. This was to pinpoint common discrepancies and to determine their causes. Methods and Results. We compared the sarcoma unit's histopathology reports with referring reports on 349 specimens from 277 patients with suspected or proven soft tissue tumours in a one-year period. Conclusions. Diagnostic agreement was found in 256 of 349 cases (73.4%), with minor diagnostic discrepancy in 55 cases (15.7%) and major discrepancy in 38 cases (10.9%). Benign/malignant discordances accounted for only 5% of all discrepancies (5 cases). The most common discrepancies occurred in tumour classification, including diagnosis of gastrointestinal stromal tumour and leiomyosarcoma and the subtyping of spindle cell sarcomas, as well as in tumour grading that could conceivably lead to changes in clinical management. Major diagnostic discrepancies leading to management change occurred in a relatively select range of tumour groups, and almost all discrepancies occurred due to differences in tumour interpretation between general or nonsoft tissue pathologists, and pathologists at the specialist unit. The findings support guidelines by the National Institute for Health and Clinical Excellence that diagnostic review of soft tissue tumours should be performed by specialist soft tissue pathologists.

When is a GIST not a GIST? A case report of synchronous metastatic gastrointestinal stromal tumor and fibromatosis

Background

A number of non-malignant diseases that share similar morphological features as gastrointestinal stromal tumor (GIST) have been reported. Co-existence of GIST with these other diseases is rarely recognized or reported.

Case presentation

We report a case of a 62 year-old man with long-term stable control of metastatic GIST with systemic therapy, presented with an apparent intra-abdominal progression but not supported by imaging with positron emission tomography. Subsequent resection of the intra-abdominal tumor identified a non-malignant fibroid.

Conclusion

Differentiating localized progression of GIST from other diseases has important prognostic and therapeutic implications. The potential for co-existence of non-malignant soft tissue neoplasm should always be considered.

Expression of melanoma antigens in epithelioid gastrointestinal stromal tumors: a potential diagnostic pitfall

CONTEXT

Most gastric gastrointestinal stromal tumors (GISTs) express CD117/c-kit, as do a subset of metastatic melanomas, leading to a diagnostic dilemma in some cases.

OBJECTIVE

To further differentiate GISTs from melanoma, we investigated expression of melanoma markers in GISTs using a well-characterized set of gastric lesions on tissue microarrays.

DESIGN

Tissue microarrays from paraffin-embedded tissue cores from 38 patients were stained with S100 protein, HMB-45, and Melan-A antibodies. All cases had been previously stained with CD117/c-kit and CD34 antibodies. All were reactive with CD117/c-kit, and 88.2% expressed CD34.

RESULTS

S100 protein was focally expressed in 2 (5.3%) of 38 GISTs; these lesions lacked HMB-45 and Melan-A labeling. No tumor labeled with HMB-45, but 4 (10.6%) of 38 cases labeled with Melan-A antibodies. The Melan-A-reactive cases were all S100 negative and CD34 positive. The S100-reactive cases were spindle cell neoplasms, whereas the Melan-A-reactive cases were epithelioid neoplasms (4/9; 44%). An additional 15 standard sections of separate cases of epithelioid GISTs were then labeled with Melan-A, and 5 (33%) of 15 showed at least focal labeling.

CONCLUSIONS

Melan-A staining can be encountered in a subset of epithelioid GISTs, a finding that can suggest a differential diagnosis of melanoma. In this series, the Melan-A-reactive cases lacked S100 protein and expressed CD34, both of which would be unlikely in melanoma. As such, a panel approach is best in differentiating epithelioid GISTs from melanoma.

Application of immunohistochemistry to soft tissue neoplasms

CONTEXT

Soft tissue tumors are composed of numerous and complex diagnostic entities. Because of this complexity and the recognition of an intermediate malignancy category including some tumors with a deceptively bland histologic appearance, soft tissue tumors may represent a major diagnostic challenge to the general practicing pathologist.

OBJECTIVE

To correctly diagnose soft tissue tumors with the ancillary use of immunohistochemistry.

DATA SOURCES

Review of the current literature with emphasis on those tumors for which immunohistochemistry has proven to be particularly useful.

CONCLUSIONS

Immunohistochemistry plays an important role in the diagnosis of soft tissue tumors. One of its major utilities is to correctly identify a tumor as being of mesenchymal or nonmesenchymal origin. Once mesenchymal origin has been established, histologic subtyping according to specific cell lineage may be achieved with the use of lineage-specific markers. Tumors of uncertain cell lineage and tumors with primitive small round cell morphology are often characterized by a unique immunohistochemical phenotype. In this group of tumors, immunohistochemistry is most widely applied and is of greatest value. Despite the rapid development of molecular genetic techniques, immunohistochemistry still remains the most important diagnostic tool in the diagnosis of soft tissue tumors aside from recognition of morphologic features and clinical correlation.