The reappraisal of gastrointestinal stromal tumors: from Stout to the KIT revolution

Carcinoma of Unknown Primary Origin: Application of Immunohistochemistry With Emphasis to Different Cytokeratin 7 and 20 Staining Patterns

BACKGROUND

Although the primary origin of some carcinomas may be obscure to clinicians, its identification is crucial as it affects prognosis and treatment (especially novel targeted therapies). Immunohistochemistry (IHC) may be helpful in identifying the primary origin of carcinomas. This retrospective survey aimed to evaluate the frequency and accuracy of each IHC marker used to determine the origin of carcinomas.

METHODS

The review of pathology department archives revealed 307 cases of cancer of unknown primary origin (CUP) between 2015 and 2020, which were accessible in the department archives. Demographic information, site of biopsy, clinical and pathologic diagnoses, and IHC results of the patients were collected.

RESULTS

The patients included 157 (51.15%) men and 150 (48.85%) women. The age of the patients ranged from 14 to 92 years, including 106 (34.5%) expired cases. In 27% of cases, the primary origin of carcinoma remained unknown. The agreement between pathologic and clinical diagnoses was 59%. The most common pattern of cytokeratin (CK) expression in CUP was CK7+/CK20- (55.3%), followed by CK7-/CK20- (19%), CK7+/CK20+ (15%), and CK7-/CK20+ (10.7%), respectively.

CONCLUSION

The IHC analysis may improve the diagnosis of CUPs. However, the origin of some cases remains unknown despite an IHC analysis, thereby necessitating the use of more diagnostic procedures or gene expression studies for reaching a definitive diagnosis.

Retrospective analysis of prognostic factors affecting the recurrence and disease-free survival following surgical management of gastrointestinal stromal tumors

Objectives

The aim of this study was to evaluate the prognostic factors effecting recurrence risk and disease-free survival of the patients who were diagnosed as gastrointestinal stromal tumor after complete resection of the tumor with or without adjuvant therapy.

Material and Methods

Between the years 2005 and 2013, data of 71 patients including clinical and demographic features, tumor localizations, pathologic examinations, survival and recurrence rates were enrolled into this retrospective study.

Results

Male/female ratio was 1.71, and mean age was 60.27 ± 14.65 years. Forty-two (59.2%) patients had tumor in stomach, 16 (22.5%) in small bowel, whereas 12 (16.9%) had extra-gastrointestinal system and one patient (%1.4) had rectal localization. Modified NIH risk stratification scheme categorized 9 (12.68%) patients in very low-, 12 (16.90%) in low-, 21 (29.58%) patients in moderate-and 29 (40.85%) patients in high-risk group. Twenty-four (33.8%) patients had a metastatic disease at follow-up while 13 (18.3%) patients were metastatic at admission. R0 resection was successfully performed in 51 (71.8%) patients, while R1 resection in 9 (12.7%) and R2 resection in 11 (15.5%) were achieved. Mean follow-up time was 47.12 ± 33.52 months (range, 1-171 months). Nineteen (26.8%) patients demonstrated recurrence with a mean time of 22.16 ± 15.89 months (range, 3-57 months). During follow-up 17 (23.9%) patients were deceased. In univariate analysis, high-risk group, small bowel and extra-gastrointestinal system localization, R1-2 resection, necrosis, positive resection margin and invasion of surrounding tissues, metastatic disease and adjuvant therapy were statistically significant in terms of recurrence. Multivariate analysis presented small bowel and extra-gastrointestinal system localization, R2 resection, mitoses count, invasion and adjuvant therapy as independent prognostic risk factors affecting disease-free survival rates. The 1, 3 and 5 years of disease-free survival rates of the patients were 89.6%, 75.4%, 64.3%, respectively.

Conclusion

As mentioned in the literature, the mainstay of curative therapy of gastrointestinal stromal tumor is surgery. In our study, not only small bowel, extra-gastrointestinal system localization and invasion of surrounding tissues by tumor, but also R2 resection that complicate the local control of the disease were represented as independent adverse prognostic factors for disease-free survival. Unfavourable clinical outcomes of adjuvant therapy over the disease-free survival was linked to higher tumor stage with metastatic disease and emphasized that prospective trials with more cases should be practiced.

Evaluation of the gastrointestinal stromal tumors for clinical features, histopathological findings and prognostic criteria: A case-control study

OBJECTIVE:

In this study, we reviewed GISTs with all morphological and immunohistochemical findings and assessed the prognostic parameters of these tumors.

METHODS:

Files of 40 cases with GIST operated between 2002 and 2008 were retrospectively examined in this study. Patients were grouped as patients with and without recurrence within postop 1 year. The patients were grouped based on their localization, gender and age. The cases were stratified as the risk grades based on risk categorization table developed by Fletcher et al. according to the tumor diameter and number of mitoses. The cases were immunohistochemically investigated for CD117, CD34, S100, and Ki-67.

RESULTS:

Male/female ratio was 25/15. The mean age was 61.55. Mean tumor diameters were statistically significantly higher in the recurrence (+) group than in the recurrence (-) group (p=0.048). The mean number of mitoses was statistically significantly higher in the recurrence (+) group than in the recurrence (-) group (p=0.038). No statistically significant difference was found in histological distribution of the recurrence (-) and recurrence (+) groups (p=0.8795). No statistically significant difference was found in CD34, S100, and Ki-67 distribution of the recurrence (-) and recurrence (+) groups (p=0.862, p=0.609, and p=0.023, respectively). All patients in the recurrence (+) group were in the high-risk group.

CONCLUSION:

GISTs are studied in a wide range from benign, incidental tumors to malignant tumors with the risk for recurrence and metastasis concerning biological behaviour. GISTs have prognostic parameters, such as tumor localization, tumor diameter, mitotic index, cellularity, and pleomorphism grade.

An Unusual Gastrointestinal Stromal Tumor Presentain: Breast, Liver and Lymph Node Metastasis

Gastrointestinal Stromal Tumors (GIST) are the common mesenchymal tumors of gastrointestinal tract. They can display benign and malignant clinical behavior. The most common metastasis sites of malignant stromal tumor are liver, peritoneum, lung and bones. Metastasis to breast is extremely rare. Here, we present a case of GIST with liver, bone, lymph node and breast metastasis by reviewing the literature.

Diagnosis value of CD117 and PDGFRA, alone or in combination DOG1, as biomarkers for gastrointestinal stromal tumors

BACKGROUND

To explore the diagnostic values of CD117 and PDGFRA protein expressions, used alone or in combination with DOG1 protein, for gastrointestinal stromal tumors (GIST).

METHODS

The CD117, PDGFRA and DOG1 protein expressions in 99 GIST specimens and 25 non-GIST specimens were retrospectively determined, and the potential correlations were analyzed.

RESULTS

The positive rates of CD117, PDGFRA, and DOG1 expressions were 93.94% (93/99), 53.54% (53/99), and 90.91% (90/99) in GIST group and 4.00% (1/25), 4.00% (1/25), and 12.00% (3/25) in non-GIST group (all P<0.05). The expressions of CD117, PDGFRA, and DOG1 had no significant correlation with clinicopathological parameters including gender, age, tumor diameter, tumor location, histotype, and risk degree (all P>0.05). The sensitivities of CD117, PDGFRA, DOG1, CD117 + DOG1, PDGFRA + DOG1, and CD117 + PDGFRA + DOG1 were 0.989, 0.981, 0.968, 0.960, 0.933, and 0.961 in judging GIST, respectively, and the specificities were 0.800, 0.343, 0.710, 0.840, 0.947, and 0.955, respectively. The areas under the ROC curve (AUC) in these six groups were 0.945, 0.748, 0.895, 0.895, 0.840, and 0.975, respectively.

CONCLUSIONS

The populations that may benefit more from the detection of CD117, PDGFRA, and DOG1 protein expression for GIST need to be further identified. Detection of CD117 and PDGFRA protein, alone or in combination with DOG1, may increase the accuracy of GIST diagnosis.

Gastrointestinal stromal tumor: 15-years' experience in a single center

Background

Gastrointestinal stromal tumor (GIST) is known for its wide variability in biological behaviors and it is difficult to predict its malignant potential. The aim of this study is to explore the characteristics and prognostic factors of GIST.

Methods

Clinical and pathological data of 497 GIST patients in our center between 1997 and 2012 were reviewed.

Results

Patients were categorized into very low-, low-, intermediate- and high-risk groups according to modified National Institutes of Health (NIH) consensus classification system. Among the 401 patients untreated with imatinib mesylate (IM), 5-year overall survival (OS) in very low-, low-, intermediate- and high-risk groups was 100%, 100%, 89.6% and 65.9%; and 5-year relapse-free survival (RFS) was 100%, 98.1%, 90.9% and 44.5%, respectively. Univariate analysis revealed that sex, tumor size, mitotic rate, risk grade, CD34 expression, and adjacent involvement were predictors of OS or RFS. COX hazard proportional model (Forward LR) showed that large tumor size, high mitotic rate, and high risk grade were independent risk factors to OS, whereas high mitotic rate, high risk grade and adjacent organ involvement were independent risk factors to RFS. The intermediate-high risk patients who received IM adjuvant therapy (n = 87) had better 5-year OS and RFS than those who did not (n = 188) (94.9% vs. 72.1; 82.3% vs. 56.3%, respectively). Similarly, advanced GIST patients underwent IM therapy (n = 45) had better 3-year OS and 1-year progression-free survival (PFS) than those who didn’t (n = 42) (75.6% vs. 6.8%; 87.6% vs. 12.4%, respectively).

Conclusions

Very low- and low-risk GISTs can be treated with surgery alone. Large tumor size, high mitotic rate, high risk grade, and adjacent organ involvement contribute to the poor outcome. IM therapy significantly improves the survival of intermediate-high risk or advanced GIST patients.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2482-14-93) contains supplementary material, which is available to authorized users.

Prognostic value of NF-κB, CD9, and VEGF in gastrointestinal stromal tumors

AIM OF THE STUDY

Gastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal tumors of the gastrointestinal system. We aimed to determine whether nuclear transcription factor κB (NF-κB), CD9 and vascular endothelial growth factor (VEGF) have prognostic value in patients with GIST.

MATERIAL AND METHODS

Thirty-five patients with GIST, who were diagnosed in the Pathology Department of Erciyes University, were included in the study. Cases were classified based on the 2002 NIH consensus. CD9, VEGF, and NF-κB immunohistochemistry were applied to GIST cases positive for CD117 and CD34, which are used to evaluate GISTs immunohistochemically.

RESULTS

Although there are no statistically significant differences between NF-κB (p = 0.329), CD9 (p = 0.269), and VEGF (p = 0.372) and risk groups, 79.22% of cases that stained positive for NF-κB, 81% of cases that stained positive for CD9, and 80% of cases that stained positive of VEGF were in the high risk group.

CONCLUSIONS

It was found that NF-κB, CD9, and VEGF, which are important in predicting behaviors of other malign tumors, were expressed at high rates in high risk group GISTs. This can be used to determine prognosis with tumor diameter, mitosis rate under 50 BBS, Ki-67 proliferation index and other parameters.

Primary gastrointestinal stromal tumors: Current advances in diagnostic biomarkers, prognostic factors and management of its duodenal location

Gastrointestinal stromal tumors (GIST) constitute 1-3% of all gastrointestinal malignancies and is the most common mesenchymal tumor of the gastrointestinal tract. Although GIST were first described in the literature in the year 1941, important advances of kit mutation and tyrosine kinase inhibitors were not made to understand and manage GIST until the last decade. Here current advances in research of possible cellular origin, diagnostic biomarkers and prognostic factors of primary GIST are reviewed, and the management of primary duodenal GIST is focused on due to its specific location. It is possible that personalized assessment and therapy will turn out to be another milestone for primary GIST.

Thoracoscopic treatment of benign esophageal tumors

Introduction

Gastrointestinal stromal tumors are among the most frequent mesenchymal tumors of the gastrointestinal tract; the incidence of these tumors in the esophagus is less than 5%. Prognosis depends on localization, size, mitotic activity and possible invasion of surrounding structures. Minimally invasive surgery may be maximally utilized for removal of these tumors from the esophageal wall. This operation is usually performed thoracoscopically or laparoscopically and using the “rendez-vous” method – with endoscopic navigation.

Aim

To evaluate a set of patients with benign tumor of the esophagus who were operated on at the First Department of Surgery from 2006 to 2011.

Material and methods

In the years 2006-2011 a total of 11 patients with benign tumors of the esophagus underwent operation.

Results

Of the 11 patients with esophageal tumor, 5 were diagnosed with gastrointestinal stromal tumor, 5 with leiomyoma and in one patient the lesion was described as heterotopy of the pancreas. We used the minimally invasive rendez-vous method with endoscopic navigation in 9 cases. All patients healed primarily and were released from hospital on the 4^th-7^th day. These patients are being followed up as outpatients and recurrence of the tumor has not been observed in any of them.

Conclusions

Minimally invasive treatment of benign tumors of the esophageal wall is considered to the method of choice. Due to possible complications and the need for subsequent therapy in some patients, these procedures should be centralized to departments with experience in esophageal, thoracic and minimally invasive surgery.

Immunohistochemical features of the gastrointestinal tract tumors

Gastrointestinal tract tumors include a wide variety of vastly different tumors and on a whole are one of the most common malignancies in western countries. These tumors often present at late stages as distant metastases which are then biopsied and may be difficult to differentiate without the aid of immunohistochemical stains. With the exception of pancreatic and biliary tumors where there are no distinct immunohistochemical patterns, most gastrointestinal tumors can be differentiated by their unique immunohistochemical profile. As the size of biopsies decrease, the role of immunohistochemical stains will become even more important in determining the origin and differentiation of gastrointestinal tract tumors.

Maspin expression in gastrointestinal stromal tumors

BACKGROUND

To investigate the role of maspin expression in the progression of gastrointestinal stromal tumors, and its value as a prognostic indicator.

METHODS

In the study 54 patients with GIST diagnosis were included in Uludag University of Faculty of Medicine, Department of Pathology between 1997-2007. The expression of maspin in 54 cases of gastrointestinal stromal tumor was detected by immunohistochemistry and compared with the clinicopathologic tumor parameters.

RESULTS

The positive expression rates for maspin in the GISTs were 66.6% (36 of 54 cases). Maspin overexpression was detected in 9 of 29 high risk tumors (31%) and was significantly higher in very low/low (78.6%) and intermediate-risk tumors (63.6%) than high-risk tumors.

CONCLUSIONS

Maspin expression might be an important factor in tumor progression and patient prognosis in GIST. In the future, larger series may be studied to examine the prognostic significance of maspin in GISTs and, of course, maspin expression may be studied in different mesenchymal tumors.

Multiple gastrointestinal stromal tumors and lipomatosis

In this report, we describe a 36-year-old man with the synchronous occurrence of multiple gastric gastrointestinal stromal tumors and multiple intestinal lipomas. Multiple, small, and well-circumscribed gastric gastrointestinal stromal tumors (3 mm to 2 cm) were present within the gastrectomy specimen. The gastrointestinal stromal tumors were composed of epithelioid cells that were strongly positive for CD117 but negative for S100 protein or smooth muscle-specific actin. Also, 17 small submucosal lipomas were identified in the duodenal portion of the gastrectomy specimen. Endoscopic follow-up of the patient revealed more than 20 additional lipomas scattered throughout the intestine. Several large intestinal lipomas were resected endoscopically and histologically confirmed. Although both multicentric gastrointestinal stromal tumor and gastrointestinal lipomatosis have been reported in association with a few genetic syndromes, there has been no report, to our knowledge, of their coexistence. We feel that the coexistence of multiple lesions of these 2 rare diseases in this relatively young patient may represent a novel syndrome.

KIT, PDGFRalpha and EGFR analysis in nephroblastoma

Nephroblastoma prognosis has dramatically improved, but an unfavourable prognostic subgroup warrants development of novel therapeutic strategies. Selective KIT, PDGFRalpha and epidermal growth factor receptor (EGFR) tyrosine kinase inhibition evolved as powerful targeted therapy for gastrointestinal stromal tumours and non-small-cell lung cancer. To investigate a potential role for tyrosine kinase inhibition, we analyzed 209 nephroblastomas for immunohistochemical KIT and EGFR expression, 63 nephroblastomas for mutations in KIT exons 9, 11, 13, EGFR exons 18, 19, 20 and 21, and all 209 nephroblastomas for PDGFRalpha exons 12, 14 and 18. Twenty-two tumours (10.5%) expressed KIT, 31 (14.8%) EGFR, and 10 (4.8%) both KIT and EGFR, respectively. KIT expression was relatively more common among high-risk tumours (6/27; 22.3%) compared to low-/intermediate-risk tumours (26/181; 14.4%). Nine patients deceased, four of which had high-risk tumours with KIT expression in two of four and EGFR expression in one of four. There were no KIT, PDGFRalpha or EGFR mutations. Our results suggest no significant contribution of KIT, EGFR or PDGFRalpha mutations to nephroblastoma pathogenesis. Despite a trend towards association of immunohistochemical KIT and EGFR expression with poor outcome in high-risk nephroblastomas, statistical analysis did not yield significant correlations in this subgroup. Therefore, it remains open if KIT, PDGFRalpha or EGFR tyrosine kinase inhibition constitute a therapeutic target in nephroblastoma in the absence of KIT, PDGFRalpha or EGFR mutations.

Mesenchymal tumor of the pancreas: report of a case

Mesenchymal tumors of the pancreas are rare and difficult to classify. We report a case of a solitary mesenchymal tumor in the body of the pancreas. The tumor showed immunocytochemical reactivity for anti-vimentin, anti-alpha-smooth muscle actin, and anti-CD34; however, it was negative immunohistochemically for antibodies to cytokeratins, as well as for the following antibodies: anti-desmin, anti-S-100, anti-chromogranin A, anti-CD117 (c-Kit), anti-CD99, and anti-bcl-2. This tumor could not be classified as a specific type of mesenchymal tumor immunocytochemically.

Gastrointestinal stromal tumors: usefulness of immunohistochemistry, flow cytometry and fluorescence in situ hybridization

BACKGROUND AND AIMS

Gastrointestinal stromal tumors (GIST) constitute a group of primary mesenchymal tumors of the gastrointestinal tract, known for their diversity in clinical behavior and the difficulties in determining malignancy and prognosis. This retrospective study evaluated a series of GIST by means of immunohistochemical techniques, flow cytometry and fluorescence in situ hybridization (FISH).

METHODS

Nine patients with GIST were analyzed for tumor size, mitotic count and CD117, CD34, MIB-1 with immunohistochemistry. In addition, the GIST were tested with FISH for chromosomes 8 and 17 and DNA index was evaluated by flow cytometry.

RESULTS

The findings confirmed the usefulness of CD117 and CD34 in diagnosing GIST and the prognostic role of MIB-1, but do not support a correlation between aneuploidy in flow cytometry and poor outcome. The FISH results suggest close follow-up for patients with benign GIST with a numerical alteration of chromosome 8. The technique could select patients with tumors at high-risk with aneusomy of chromosome 17.

CONCLUSION

This study shows the possible application of FISH to the evaluation of patients with GIST, in addition to analysis of morphological features.

Gastrointestinal stromal tumors of the rectum: Clinical, pathologic, immunohistochemical characteristics and prognostic analysis

OBJECTIVE

To describe the clinical, pathological and immunohistochemical characteristics of rectal gastrointestinal stromal tumors (GISTs) and to correlate them with clinical outcomes.

MATERIAL AND METHODS

A retrospective review of 29 patients with surgically treated rectal GISTs during the period from 1997 to 2005 was undertaken. The NIH (National Institute of Health Consensus) criteria were applied.

RESULTS

All the rectal GISTs in our series originated in the lower half of the rectum and patients underwent primary surgery for complete resections; High-risk, intermediate-risk, low-risk and very low-risk GISTs were found in 11, 6, 5 and 7 patients, respectively. Necrosis, adjacent (mucosal or serosa) invasion and marked pleomorphisms were found in 10, 7 and 20 patients, respectively. Positive expression of CD117, CD34, SMA and S-100 was found in 28, 28, 7 and 3 patients, respectively. Twelve patients had recurrence or metastasis within the median disease-free survival time of 41 months. Among the patients who underwent local resections, the recurrence rate for low-risk and very low-risk GISTs was only 1/10; for intermediate-risk and high-risk GISTs, the recurrence rate after local resections was 3/4, which was higher than the recurrence and metastasis rate of 8/13 after laparotomy. Of the 12 patients with adverse outcomes, 4 patients underwent secondary complete resections; however, all 4 patients had further recurrences. On univariate analysis, risk classification (p = 0.0002), necrosis (p = 0.0205), adjacent invasion (p = 0.0090) and marked pleomorphism (p = 0.0480) were significant predictors of disease-free survival. In the Cox regression model, only the risk classification (p = 0.012) was found to be an independent factor.

CONCLUSION

We found that rectal GISTs arise predominantly in the lower half of the rectum and have high CD117 and CD34 expression. Local resection may be a good choice for very-low-risk and low-risk GISTs, but aggressive surgery may be more beneficial for high-risk and intermediate-risk GISTs. For patients with disease recurrence, the results of secondary surgery were poor. Only the NIH risk classification proved to be an independent prognostic factor for rectal GISTs, whereas the proof for other factors was insufficient.

Tumor size is a major determinant of recurrence in patients with resectable gastrointestinal stromal tumor

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumor of the gastrointestinal tract. Surgery remains the mainstay of curative treatment. Recurrence after surgery was frequent and was associated with poor prognosis. In this study, we tried to identify predictors of recurrence in resectable GISTs.

METHODS

Between January 1995 and December 2005, 100 patients undergoing surgical resection for GISTs in 2 hospitals were studied.

RESULTS

There were 67 gastric and 33 intestinal GISTs. Recurrence was noted in 11 patients (median follow-up of 43 months). Overall 5-year survival was 84%. Multivariate analysis demonstrated that tumor size > or = 10 cm was associated with higher recurrence rates (P = .032) and was the only independent poor prognostic factor for survival (P = .020).

CONCLUSIONS

We concluded that tumor size > or = 10 cm carried both a higher risk of recurrence and worse survival in resectable GISTs and could be considered an indicator for adjuvant therapy.

Significance of CD44 expression in gastrointestinal stromal tumors in relation to disease progression and survival

BACKGROUND

CD44 is a transmembrane glycoprotein belonging to the cell-adhesion molecule family. It has been identified as being involved in tumor progression and metastasis, and its expression has been found to be of prognostic significance in several human malignancies. The aim of this study was to assess CD44 expression in gastrointestinal stromal tumors (GISTs), the most common mesenchymal tumor of the gastrointestinal tract.

METHODS

Between January 1995 and March 2006, 92 patients undergoing surgical resection for GIST in National Cheng Kung University Hospital were evaluated. To study the significance of CD44 expression, immunohistochemical staining of CD44 in tumor specimens was performed, and the clinicopathological information of patients was reviewed.

RESULTS

Fifty-nine of 81 patients (73%) showed positive CD44 expression. Loss of CD44 expression was associated with disease progression (p = 0.019). Kaplan-Meier analysis revealed better progression-free survival among patients with strong CD44 expression (++ and +++) (p = 0.034), absence of disease progression (p < 0.001), and lower risk, according to National Institutes of Health (NIH) Consensus Criteria for GIST risk stratification (p = 0.003). Multivariate analysis demonstrated that high-risk status was the only independent risk factor for disease progression and the only independent predictor for a poor progression-free survival (p = 0.023 and 0.045, respectively).

CONCLUSIONS

It is demonstrated that high-risk status by NIH criteria is significantly associated with disease progression and poor progression-free survival in GIST.

Gastrointestinal stromal tumors: a contemporary review

The literature on gastrointestinal stromal tumors (GISTs) has rapidly expanded and has demonstrated how scientific advancements in diagnosis can revolutionize the understanding of disease, while paving the way for effective treatment. While KIT (CD117) immunohistochemistry has established our definition of GISTs, molecular genetics continue to refine it. Elucidation of the aberrant receptor tyrosine kinase (RTK) model of GIST pathogenesis through mutations in c-kit and platelet-derived growth factor alpha PDGFRalpha proto-oncogenes has been prerequisite to the use of imatinib mesylate (STI571, Gleevec; Novartis, Switzerland), a molecular inhibitor of several tyrosine kinases, in the treatment of GISTs. In addition to providing a means for effective treatment, clarification of the molecular pathology of GISTs may potentially offer a new classification of these tumors by correlating genotype with histological, immunohistochemical, and clinical phenotype. This article seeks to review current knowledge of GISTs, offering a practical guide to their diagnosis and describing current epidemiological, molecular biological, and therapeutic aspects.

[Gastrointestinal stromal tumors: definition, histological, immunohistochemical, and molecular features, and diagnostic strategy]

Gastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal tumors of the gastrointestinal tract. Major advances in their definition and classification and the understanding of their molecular mechanisms have recently been made. These advances have resulted in the delineation of a treatment that has become a model of targeted therapy in oncology. GISTs are defined as tumors of the gastrointestinal tract, but also of the mesentery and peritoneum, constituted by a proliferation of usually spindle-shaped, rarely epithelioid cells, usually, but not consistently expressing the KIT protein. Most GISTs are associated with molecular abnormalities in two target genes: KIT (which encodes the KIT protein) and PDGFRA (which encodes the A chain of the PDGF receptor). The diagnosis of GIST relies on histological arguments (proliferation of spindle-shaped cells in 70% of cases, of epithelioid cells in 20%; histological variants are rare and sometimes misleading) and on immunohistochemical arguments (expression of KIT in 95%, usually associated with CD34 expression in 60%-70% of cases). The demonstration of mutations in target genes is required only in cases that are histologically suggestive but KIT-negative; beyond this indication, this is only undertaken in research protocols. The differential diagnosis of GIST includes the other mesenchymal tumors of the gastrointestinal tract, such as leiomyomas and leiomyosarcomas, and the digestive locations of some sarcomas; it relies on both histological and immunohistochemical arguments. The evaluation of the prognosis is essential. According to the current concept, every GIST carries a risk of malignancy, which may vary from very low to very high. Prognosis is based on a simple algorithm using two histoprognostic parameters, i.e., tumor size and mitotic index. The treatment of localized GIST is surgical resection, which must be complete; that of advanced or unresectable GIST is based on the use of a targeted therapy, imatinib, which is a pharmacological antagonist of the KIT protein. Proper understanding and utilisation of the diagnostic criteria and classification of GIST by pathologists are essential for good patient management.

Expression of HER1/EGFR protein in human soft tissue sarcomas

AIM

To measure epidermal growth factor receptor (HER1/EGFR) expression in a range of soft tissue sarcoma (STS) patient samples.

METHOD

HER1/EGFR expression was examined by immunohistochemistry in archival tissues of 46 STS patients.

RESULTS

HER1/EGFR was positively expressed in 36/46 of STS samples distributed among different histological types. The levels of HER1/EGFR in STS tumour tissues in positive samples were higher compared to those in nearby normal tissues.

CONCLUSION

HER1/EGFR is significantly expressed in soft tissue sarcomas, which is a finding reflected in other series. The significance of this finding for targeted therapy is as yet unknown.

About a case of GIST occurring during pregnancy with immunohistochemical expression of epidermal growth factor receptor and progesterone receptor

The coexistence of gastrointestinal stromal tumors (GISTs) and pregnancy is very rare. We are the first to add to the literature a case report of GIST occurring during pregnancy with immunohistochemical staining for epidermal growth factor receptor (EGFR) and progesterone receptor (PgR). A role of PgR and EGFR in tumor growth should not be excluded, and these findings indicate that the expression of these receptors could provide pertinent biological information required to determine adequate therapeutic regimens. In conclusion, considering that GIST occurring during pregnancy is a rare event, with frequent delay in diagnosis, it is important to consider this diagnosis for early recognition, correct diagnosis, and a better outcome.

Polypoid pleomorphic sarcoma of the colon

In contrast to common colonic epithelial neoplasms, polypoid mesenchymal tumors of the colon are extremely rare. The majority of uncommon gastrointestinal mesenchymal tumors are associated with the so-called gastrointestinal stromal tumors (GIST). We present a case of a rare colonic pleomorphic sarcoma, macroscopically mimicking a common epithelial colonic polyp, which did not match the criteria of GIST. In this case report we discuss the clinical and pathological characteristics of a rare polypoid-shaped, pleomorphic colonic sarcoma and refer a mark-off to other rare mesenchymal neoplasms of the gut.

Colorectal mesenchymal tumor: a clinicopathologic study of 25 cases

BACKGROUND

It is important to distinguish gastrointestinal stromal tumors (GISTs) from other gastrointestinal mesenchymal tumors (GIMTs), because of the malignant potential of GISTs and the availability of molecular targeted therapy. GISTs represent the most common subgroup of GIMTs, and rarely occur in the colon and rectum. The first objective of our retrospective study was to reclassify colorectal mesenchymal tumors, from files collected over 20 years, to determine if, based on immunohistologic features, the lesions were truly GISTs. The second objective was to identify the relationship between clinicopathologic features and prognostic factors of GISTs in the colon and rectum.

METHODS

We evaluated all cases of colorectal mesenchymal tumor identified from the database of the Department of Surgical Pathology at Taichung Veterans General Hospital for the period 1983-2001. For 25 patients, clinical data, and information about tumor characteristics, surgical procedures, and survival outcomes, were obtained and analyzed. Histopathologic evaluations, and appropriate immunohistochemical markers, were used to distinguish between various GIMT subtypes. The relationship between KIT expression and clinicopathologic features was investigated.

RESULTS

The following variables were significantly associated with different CD117 results: symptomatic presentation, location, gross features, tumor size, mitotic count, cellularity, and type of surgery. Only 18 tumors were identified as GISTs. For these, the following variables were significantly associated (by univariate analysis) with increased lethality: tumor size (p = 0.049); mitotic count (p = 0.019); nuclear atypia (p = 0.019); and tumor necrosis (p = 0.045). However, only mitotic activity showed a significant difference in the survival analysis (p = 0.0304; log-rank test).

CONCLUSION

Two clinicopathologically different categories were identified from our colorectal mesenchymal tumors: intramural GISTs and polypoid submucosal leiomyomas. Our study suggests that GIST is a better categorization than smooth muscle tumor because of the malignant potential. Prognosis is strictly related to the number of mitoses. However, tumor size, nuclear atypia and tumor necrosis are probably also significant predictive factors of lethality. Future studies with DNA analysis and larger patient numbers are essential to evaluate the prognostic significance of our findings.

Reactive nodular fibrous pseudotumors of the gastrointestinal tract: report of 8 cases

Eight cases of reactive nodular fibrous pseudotumor of the gastrointestinal tract are presented. The patients included 6 males and 2 females between the ages of 1 and 68 years (mean age 41.5 years). Three tumors involved the small intestine, and 5 of the investigated lesions were located in the large bowel. Of these, 2 originated in the sigmoid colon, 1 in the cecum, 1 in the appendix, and 1 in the large bowel not otherwise specified. The tumors' size varied from 3 to 10 cm in the greatest diameter (mean 6.2 cm). Histologically they were composed of stellate or spindle shaped cells resembling fibroblasts arranged haphazardly or in intersecting fascicles, embedded in a collagen-rich stroma, with sparse intralesional mononuclear cells frequently arranged in lymphoid aggregates. Immunohistochemically, the lesions were positive for vimentin (7/7), smooth muscle actin (8/8), muscle-specific actin (5/7), cytokeratins AE1/AE3 (6/7), and CAM 5.2 (1/7), and antigen CD68 (1/7). No case (0/8) reacted positively with antibody to CD117 (c-kit). Genetically no substitutions, deletions, or insertions occurred in exon 11 in all analyzed samples. Likewise, no deletions or insertions in part of exon 9 were observed. Ultrastructurally the tumor cells revealed features typical of myofibroblasts. According to the morphologic, immunohistochemical, and ultrastructural features mentioned above, especially to the positivity of low-molecular-weight cytokeratins, we propose this lesion to be related to a proliferation of multipotential subserosal cells rather than ordinary myofibroblasts or fibroblasts.

Changing concepts in the pathological basis of soft tissue and bone sarcoma treatment

Though soft tissue sarcomas are rare considerable progress has been made in the clinical and biological understanding of these neoplasms. This has led to the launch of a new WHO classification of soft tissue tumours in 2002, which integrate morphological data with tumour specific (cyto-) genetics. Moreover worldwide consensus has grown how to predict clinical behaviour based on a specific grading system and which specific types of tumours seem not to obey these rules. As a consequence entry criteria for multi-institute prospective trials have changed over the last few years. The recent identification of tumour specific drug targets by immunohistochemistry has had impact on specimen requirements and handling as well as laboratory standards. These changes in concepts, classification, and processing of soft tissue sarcomas have had impact on patient selection and treatment and formats of multi-institute trials.

Gastrointestinal stromal tumors (GISTs)

PURPOSE OF REVIEW

Gastrointestinal stromal tumors (GISTs) have recently been the subject of considerable clinical and experimental interest. This focus is based on the recognition that GISTs characteristically have uncontrolled activation of the KIT protein, a transmembrane tyrosine kinase receptor involved in cell survival, development, and proliferation. The clinical application of imatinib mesylate, a selective inhibitor of the KIT kinase activity, has provided a novel molecularly targeted therapy for these tumors. This review summarizes publications from the last year regarding these tumors.

RECENT FINDINGS

Recent studies have focused on imaging, the identification of prognostic factors and molecular events, and the role of systemic therapy in the treatment of these tumors. Emerging data suggest that the combination of endoscopic ultrasound and fine-needle aspiration analysis for KIT expression may be useful in separating these lesions from other submucosal lesions of the gastrointestinal tract. The benefits and limitations of computed tomography and positron emission tomography in identifying, staging, and evaluating the response to therapy of these lesions have been more clearly defined. Although tumor size and the number of mitoses remain the best prognostic markers, several studies reported provocative data using other markers such as Ki-67, p53, and alterations in p16. Mutational analysis of the KIT oncoprotein continues to be the subject of considerable interest in relation to both prognosis and resistance to therapy. Finally, a series of new studies have confirmed the benefits and better defined the results of therapy with imatinib mesylate. There is increasing interest in expanding the role of this agent into the adjuvant setting and in combining such therapy with reoperation for responsive disease.

SUMMARY

In the past year there have been significant developments in our understanding of GISTs and their response to therapy. Many questions remain unanswered and new issues have arisen as the benefits of imatinib mesylate therapy are revealed. There is considerable optimism that the targeted molecular approach being applied to the treatment of GISTs will serve as a model for the development of similar approaches to other more common tumors.