Cytologic diagnosis of gastrointestinal stromal tumor with emphasis on the differential diagnosis with leiomyosarcoma

Can EUS-FNA cytology reliably classify gastric submucosal spindle cell tumors?

BACKGROUND

Cytological diagnosis using endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) for gastric submucosal spindle cell tumors, such as gastrointestinal stromal tumors (GISTs), leiomyomas, and schwannomas, is challenging because of their similar morphological characteristics.

OBJECTIVE AND MATERIALS

To clarify the cytological differential points, we reviewed the EUS-FNA cytology specimens of GISTs (37 cases), leiomyomas (11 cases), and schwannomas (4 cases).

METHOD

Twelve cytomorphological features were evaluated: lymphocytes, crushed nuclei, naked spindle nuclei, mast cell, length of the streaming arrangement, cellularity, nuclei at the cluster margin (nuclei located at the periphery of the cell cluster), peripheral feathering (loosely aggregated cells at the margin of a cell cluster tended to taper like feathers), metachromasia, wavy nuclei, fishhook-type nuclei, and anisonucleosis.

RESULTS

Among these features, lymphocytes, naked spindle nuclei, length of the streaming arrangement, cellularity, nuclei at the cluster margins, peripheral feathering, and anisonucleosis were statistically significant for differentiation. Based on these findings, we developed an algorithm for cytodiagnosis. The algorithm was taught to four cytologists, and the interobserver agreement and correct diagnosis rates were compared before and after education, which showed a significant improvement.

DISCUSSION

The histological types of gastric submucosal spindle cell tumors can be estimated using this algorithm for EUS-FNA cytology. Furthermore, this algorithm can be applied for cytological diagnosis at bedside during rapid on-site evaluation.

A Curious Case of a Posterior Mediastinal Mass

Gastrointestinal stromal cell tumors (GISTs) are mesenchymal stromal tumors that are characteristically CD117 positive. Distinction from other spindle cell tumors such as leiomyomas and leiomyosarcomas is based on clinical, histological, and molecular features. Endoscopic ultrasonography-guided fine-needle aspiration has become a highly used means of preoperative identification of GIST, especially if immunohistochemical staining for CD117 can be performed. We present a case of a posterior mediastinal mass diagnosed as GIST after being found to be CD117 positive, later found to be a metastatic leiomyosarcoma.

Spindle cell neoplasms of the upper gastrointestinal tract, hepatobiliary tract, and pancreas by fine needle aspiration: A single institutional experience of 15 years with follow-up data

BACKGROUND

The diagnosis of spindle cell neoplasms (SCN) of the upper gastrointestinal (GI) tract, hepatobiliary tract, and pancreas detected by fine needle aspiration (FNA) is challenging. We describe a single-center experience of these samples with follow-up data and characterization of the morphologic findings.

METHODS

We retrospectively reviewed pathology records for all FNAs diagnostic for or suggestive of SCN on esophagus, stomach, small bowel, liver, and pancreas in a 15 year period. All cases with at least 6 month follow-up were included. Surgical material (biopsy or resection) was the diagnostic gold standard. All FNAs with subsequent surgical specimens were reviewed and assessed for cellularity, architectural features, and nuclear features.

RESULTS

In 15 years, 5101 FNAs of the upper GI tract, hepatobiliary tract, and pancreas were performed. SCN was diagnosed in 98 (2%) patients. Seventy-two patients had definitive pathologic diagnoses: 68 were neoplastic and four were non-neoplastic. Cytomorphologic review in relationship to final diagnosis revealed three statistically significant features: low cellularity favors a benign process (P = .00544), epithelioid nuclear morphology favors malignancy (P = .00278), and identification of perinuclear vacuoles favors a diagnosis of GIST over non-GIST SCN (P = .04236).

CONCLUSIONS

Among cases with follow-up, final pathologic diagnoses were SCN in 94% of cases diagnosed as SCN on FNA of upper GI, hepatobiliary tract, and pancreas. Although some cytomorphologic criteria are more suggestive of malignancy, arriving at a specific diagnosis relies on collaboration of clinical, radiologic, cytomorphologic, and immunohistochemical data.

Fine Needle Aspiration Cytology of Malignant Digestive System Gastrointestinal Neuroectodermal Tumor in a Lymph Node Metastasis from a Previously Diagnosed Liver Primary: A Case Report and Review of Literature

Malignant gastrointestinal neuroectodermal tumor (GNET) is an extremely rare neoplasm. Immunohistochemically, GNET typically demonstrates neural differentiation but lacks melanocytic differentiation, making it distinct from clear cell sarcoma of the soft tissues (CCS). Herein we report for the first time the cytomorphologic features of lymph node metastasis from presumably liver GNET. A 36-year-old female presented with fevers, night sweats, loss of appetite, and a 20-lbs weight loss. Radiographic imaging showed a 13 cm heterogeneously enhancing mass in the right lobe of the liver and a hypermetabolic 0.9 cm periportal lymph node on positron emission tomography-computed tomography (PET/CT). Initially, a CT-guided liver biopsy was performed followed by right hepatic lobectomy and portal lymphadenectomy. The liver biopsy and resection showed an S100-protein and SOX10 positive malignant neoplasm and genomic profiling of liver biopsy revealed EWSR1-CREB1gene rearrangement. These findings in conjunction with the morphologic and immunohistochemical profile were diagnostic of GNET. Two months later, she presented with recurrent lymphadenopathy in the upper abdomen. Fine needle aspiration of the periportal nodal mass revealed single and clusters of primitive, large to medium-sized neoplastic cells with round to oval nuclei, high nuclear-cytoplasmic ratio, vesicular chromatin, and prominent nucleoli. The tumor cells were S100 protein and SOX10 positive, consistent with metastasis of the patient's recently diagnosed malignant digestive system GNET. Palliative chemotherapy was administered but the patient died a few days later, 4 months from the initial diagnosis. Awareness of this entity and judicial use of ancillary studies including molecular testing are essential for achieving accurate diagnosis.

Mesenchymal neoplasms of the tubular gut and adjacent structures: experience with EUS-guided fine-needle aspiration cytopathology

INTRODUCTION

Unlike epithelial malignancies, mesenchymal neoplasms arising within the tubular gut are less often encountered in endoscopic ultrasound-guided (EUS) fine-needle aspiration biopsies (FNABs). Nonetheless, preoperative diagnosis of such neoplasms has important therapeutic and prognostic value. We report our experience with this category of neoplasms from the past decade.

MATERIALS AND METHODS

We performed a 10-year retrospective search at our respective institutions to identify EUS-guided FNAB cases of mesenchymal neoplasms arising from the tubular gut wall and closely adjacent structures. Cytopathologic diagnoses were compared to corresponding surgical pathology (SP) when available. Cases with either no confirmatory cell block (CB) immunohistochemical (IHC) staining, or no SP were excluded.

RESULTS

Two-hundred eighty-two cases (M:F = 1:1; age range: 25-94 years, mean age = 60 years) of EUS-guided FNAB from the tubular gut met our criteria. Onsite adequacy was performed on nearly all cases. Case numbers: 209 gastrointestinal stromal tumors (GIST), 58 smooth muscle neoplasms, and 15 miscellaneous neoplasms. Of these, 188 (67%) had SP follow-up. We found that 258 (91%) aspirates had a correct specific diagnosis, 3 (1%) were nondiagnostic, 18 (6%) had indeterminate diagnoses, and 3 (1%) had incorrect diagnoses (2 leiomyosarcomas mistaken as leiomyoma, and 1 fibrosclerotic lesion mistaken as inflammatory pseudotumor). Of 94 cases with no SP, all had a specific cytologic diagnosis based on confirmatory IHC staining from the CB including 61 GISTs, 29 smooth muscle neoplasms, and 4 miscellaneous tumors.

CONCLUSION

This study endorses the clinical utility of EUS-guided FNAB in the diagnosis of tubular gut mesenchymal neoplasms. A definitive and accurate diagnosis is possible in over 90% of cases, chiefly when cytomorphology is coupled with optimal cellularity and IHC from a concurrent CB. EUS-guided FNAB diagnosis of mesenchymal tubular gut neoplasms may play an important role in determining neoadjuvant therapy as targeted therapy evolves.

Practical Application of Cytology and Core Biopsy in the Diagnosis of Mesenchymal Tumors

Soft tissue neoplasms are increasingly being sampled by core needle biopsy and fine-needle aspiration (FNA), and these small biopsy specimens pose unique diagnostic challenges. Many advances in ancillary testing enable detection of characteristic immunophenotypes and molecular alterations, allowing accurate classification of soft tissue tumors in these small biopsy samples. This review outlines pattern-based diagnostic approaches to core biopsies and FNAs of soft tissue neoplasms, including formulation of practical differential diagnoses and relevant application of ancillary tests.

Jejunal leiomyosarcoma: Report of a rare case diagnosed on cytology

Jejunal leiomyosarcomas (LMS) are extremely rare. Of all the mesenchymal tumors of the small intestine, Gastrointestinal Stromal Tumors (GIST) comprise the majority. LMS of the small intestine have been documented as isolated reports or only a very small percentage of the smooth muscle tumors of the small intestine. Furthermore, cytological evaluation and preoperative diagnosis of small intestinal LMS is not well documented, even though cytology of small intestinal GISTs has been studied. Since preoperative diagnosis is useful in differentiating benign from malignant lesions, correctly staging malignant lesions and identifying the plan of management, preoperative cytological evaluation assumes a great significance. We report a case of jejunal leiomyosarcoma diagnosed on cytology. KEY MESSAGES: Although extremely rare, small intestinal LMS should be considered in the differential diagnosis of small intestinal mesenchymal lesions. FNAC, with preparation of cell block, and subsequent IHC can help in the preoperative diagnosis and formulating a plan of management of the patients.

Applications of Ancillary Testing in the Cytologic Diagnosis of Soft Tissue Neoplasms

Soft tissue neoplasms are diagnostically challenging, although many advances in ancillary testing now enable accurate classification of fine-needle aspiration biopsies by detection of characteristic immunophenotypes (including protein correlates of molecular alterations) and molecular features. Although there are many useful diagnostic immunohistochemical markers and molecular assays, their diagnostic utility relies on correlation with clinical and morphologic features, judicious application, and appropriate interpretation because no single test is perfectly sensitive or specific. This review discusses applications of ancillary testing for commonly encountered soft tissue neoplasms in cytopathologic practice in the context of a pattern-based approach.

Clinicopathologic features and outcomes of gastrointestinal stromal tumors arising from the esophagus and gastroesophageal junction

Background

Our aim was to characterize the clinicopathological features and outcomes of gastrointestinal stromal tumors (GISTs) arising from the esophagus and gastroesophageal junction (GEJ) and describe the survival of patients treated at our institution as well as from a national hospital-based registry.

Methods

Twenty-eight cases were identified using the Mayo Clinic Cancer Registry from 1997 to 2016, and 1,010 cases from the National Cancer Database (NCDB) between 2004 and 2014, with analysis of TNM staging, histopathological features, mitotic index, immunohistochemical studies, and KIT mutational analysis.

Results

At Mayo Clinic, the tumors ranged in size from 0.3-13 cm (mean 5.40 cm). IHC results were: CD117 (KIT) in 100% (23/23 cases) and DOG1 in 100% (6/6), followed by CD34 (85.7%, 12/14), smooth muscle actin (27.8%, 5/18), desmin (18.2%, 2/11), and S-100 protein (13.3%, 2/15). Mutational analysis (performed in 10 cases) showed KIT exon 11 mutations in 8 cases; KIT mutation was not identified in 2 cases (presumed wild-type). Two-thirds of patients underwent surgery, of which 70% had an esophagectomy. Fourteen patients received adjuvant imatinib mesylate. Five patients had liver metastases at the time of diagnosis; none had lymph node metastases. A total of 38.9% of cases had recurrent or metastatic disease. Complete clinical follow-up was available for 10 patients (median follow-up duration 31.5 months; range, 10-145 months): one (male) had a local recurrence at the anastomotic site and one (female) suffered a liver metastasis; the others were either disease-free or had stable disease at the time of last follow-up. There was a significant association seen among metastatic disease and mitotic count >5/50 high-powered field (HPF) (P=0.016), with median mitotic rate 90/50 HPF (range, 7-500) for metastatic tumors versus 6/50 HPF (range, 0-100) for non-metastatic tumors. For metastatic disease, median tumor size was 7.3 cm (range, 1-66 cm) compared to 4.8 cm (range, 0.02-71 cm) for non-metastatic disease, which was also statistically significant (P≤0.0001). Two hundred and fifty-eight NCDB cases were risk stratified using the Joensuu criteria. Among 89 low risk category tumors, only 2 (2.2%) were ultimately metastatic. A total of 10.9% (15/138) of high risk category tumors were metastatic. The median overall survival (OS) from the time of diagnosis for the Mayo Clinic cohort was 129.5 months (95% CI, 55.7-not reached), with 5-year OS 85.7%. Median OS for the NCDB cohort was 135.95 months (95% CI, 104.08-not reached) with 5-year OS 68.2%. Superior OS was seen in females (HR 0.67, 95% CI, 0.49-0.89, P=0.006).

Conclusions

Among esophageal and GEJ GISTs, metastatic disease was associated with increased mitotic count and increased tumor size. Men were found to have inferior OS. The Joensuu risk criteria were validated for risk stratification of esophageal and GEJ GISTs.

Pathology of Liver Metastases

BACKGROUND

The liver is the most frequent site of metastatic disease, and metastatic disease to the liver is far more common than primary liver carcinoma in the United States. Pathologic evaluation of biopsy samples is key to establishing a correct diagnosis for patient management. Morphologic and immunoperoxidase studies, which are the standard for pathologic practice, accurately classify most tumors. Subclassification of carcinoma of unknown primary remains problematic.

METHODS

The author reviewed the literature for articles pertaining to liver biopsy, diagnosis of specific tumor types, utility of immunohistochemical markers, and microarray and proteomic analysis.

RESULTS

Sampling of liver lesions is best accomplished by combining fine-needle aspiration and needle core biopsy. Many malignancies have distinct morphologic and immunohistochemical patterns and can be correctly subclassified. Adenocarcinoma of unknown primary remains enigmatic since current immunohistochemical markers for this differential diagnosis lack specificity. Microarray analysis and proteomic analysis of tumors can provide distinct gene or protein expression profiles, respectively, for tumor classification. These technologies can be used with fine-needle aspiration and needle core biopsy samples.

CONCLUSIONS

Most metastatic malignancies in the liver may be correctly diagnosed using standard morphology and immunohistochemical techniques. However, subtyping of some carcinomas and identification of site of unknown primary remains problematic. New technologies may help to further refine our diagnostic capabilities.

A case of successful detection of disseminated gastrointestinal stromal tumors by ascites smear cytology using cell block preparation with DOG1 immunostaining

Cytological features of gastrointestinal stromal tumors (GISTs) have been reported, especially regarding fine-needle aspiration cytology, including immunostaining for c-kit and DOG1. Meanwhile, cytological findings of GISTs on ascites cytology have rarely been reported, which may be owing to the rare appearance of GIST tumor cells in ascites. Herein, we present a 66-year-old woman who had disseminated GISTs in the abdomen. The GIST tumor cells appeared sparsely in the ascites smear cytology using ascites obtained at the time of autopsy. Even when widespread intra-abdominal dissemination takes place, GISTs may be hard to detect in ascites smear cytology, based on the experience of this case. However, immunohistochemistry of DOG1 using a cell block preparation was found to clearly visualize the GIST tumor cells, although they were sparsely present. Immunostaining of c-kit did not provide as clear an identification of the tumor cells as DOG1 did. When suspicious about GISTs, it is wise to prepare a cell block to make it possible to visualize the tumor cells immunohistochemically.

Intraparietal esophageal leiomyomas diagnosed by endoscopic ultrasound-guided fine-needle aspiration cytology: Cytological and immunocytochemical features in two cases

Endoscopic ultrasound-guided fine-needle aspiration cytology (EUS-FNAC) has proven to be of significant value as a diagnostic method for the evaluation of esophageal mesenchymal tumors, such as true leiomyomas. Utilizing the cell block procedure, the present study reports the diagnostic approach of EUS-FNAC in two patients affected by this lesion, describing the cytological and immunocytochemical findings. Spindle-shaped elements with elongated nuclei were appreciable; moreover, the cytoplasmatic immunohistochemical positivity for smooth muscle actin and desmin strongly supported the diagnosis of leiomyoma when also taking into account the constant negativity for CD34, CD117 and S100. The differential diagnosis between spindle cell mesenchymal tumors and leiomyomas, and the clinico-therapeutic management of the latter are also discussed in the study.

Cytomorphology of gastrointestinal stromal tumors and extra-gastrointestinal stromal tumors: A comprehensive morphologic study

BACKGROUND

The term gastrointestinal stromal tumors (GIST) is used to refer to those mesenchymal neoplasms of the gastrointestinal tract (GIT) which express CD117, a c-kit proto-oncogene protein.

AIMS

To study the cytological features of GIST and extra-gastrointestinal stromal tumors (EGIST), to correlate them with histology and to determine cytological indicators of malignancy.

MATERIALS AND METHODS

Cytological smears from patients diagnosed as GIST/EGIST on histology were retrieved. From Jan 2000 to July 2010, 26 GIST (13 primary, 12 metastatic, one recurrent) and seven EGIST (5 primary, one metastatic, one recurrent) cytologic samples from 27 patients were identified.

RESULTS

The patients included 20 males and 7 females with a mean age of 50.6 years. Tumor sites included stomach (5), duodenum (5), ileum (2), ileocecal (1), rectum (1), liver (9), retroperitoneum (5), mesentery (1), subcutaneous nodule (1), supra-penile lump (1), ascitic (1) and pleural fluids (1). The smears were cellular with cohesive to loosely cohesive thinly spread irregularly outlined cell clusters held together by thin calibre vessels. The tumor cells were mild to moderately pleomorphic, spindle to epithelioid with variable chromatin pattern and variable cytoplasm. Cellular dyscohesion, nuclear pleomorphism, intranuclear pseudoinclusions, prominent nucleoli, mitosis and necrosis were more prominent in malignant, metastatic and recurrent tumors.

CONCLUSIONS

GISTs show a wide spectrum of cytological features and the presence of mitosis, necrosis and nuclear pleomorphism can help in prediction of malignant behavior. Further, cytology is a very useful screening modality in patients of GIST and EGIST to detect early recurrence and metastasis at follow-up.

Cytologic findings of gastric schwannoma: a case report

Spindle cell lesions of the stomach are rare. They usually affect the submucosa or muscularis propria and therefore can be sampled by endoscopic fine needle aspiration. The most common tumor in this category is gastrointestinal stromal tumor (GIST), followed by leiomyoma and gastric schwannoma. Gastric schwannoma is a benign tumor of neuroectodermal origin that has overlapping morphologic/cytologic features with GIST and leiomyoma. Gastric schwannomas differ from peripheral schwannomas by lacking a capsule, Verocay bodies, Antoni B areas, and thick-walled vessels. They are characterized morphologically by poorly defined borders, cuffs of lymphoid tissue and a haphazard spindle cell proliferation. We present here the cytologic and histopathologic features of a gastric schwannoma. The tumor was composed of spindle cells with delicate eosinophilic cytoplasm and wavy nuclei, with an associated conspicuous lymphoid backdrop. The latter feature raised the possibility of a lymphoid lesion, a problem cytopathologists should be aware of.

Increased diagnostic yield of endoscopic ultrasound-guided fine needle aspirates with flow cytometry and immunohistochemistry

Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is the most sensitive and specific test for establishing a tissue diagnosis for many gastrointestinal malignancies; however, cytologic morphology alone may not be definitive for subsets of tumors. Our aim was to quantify the impact of the broad application of flow cytometry (FC) and immunohistochemistry (IHC) on EUS-FNA diagnostic yield. A retrospective chart review was performed on EUS procedures at a tertiary referral, academic medical center. All EUS-FNA cases performed over a 21-month period were examined. Of 606 EUS procedures reviewed during the period of study, 264 utilized FNA. After pancreatic cyst cases were excluded, 235 EUS-FNA cases for 221 patients were selected for analysis. For cases with subsequent histological evaluation, including the subset utilizing FC/IHC, the sensitivity of EUS-FNA was 89%, specificity was 100%, and accuracy was 91%. One quarter (58/235, 25%) of the tissue specimens underwent further testing by FC/IHC. There were 48 definitive diagnoses made in the subset utilizing FC/IHC. In 20 of the 48 diagnoses (42%), FC/IHC was deemed critical to the diagnosis, and without FC/IHC testing in those cases, the overall sensitivity and accuracy of EUS-FNA would be reduced to 74 and 77%, respectively. FC/IHC allowed for six diagnoses rarely or not previously described by EUS-FNA. Application of FC/IHC improves characterization predominantly for nonadenocarcinoma tumor subtypes and may lead to a diagnostic result for tumors not previously characterized by EUS-FNA. With an adequate tissue sample, broad application of FC/IHC increases the diagnostic yield of EUS-FNA.

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.

DOG1 antibody is a highly sensitive and specific marker for gastrointestinal stromal tumors in cytology cell blocks

Initial diagnosis of submucosal gastrointestinal stromal tumors (GISTs) is often made from material obtained by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA). Although 95% of GISTs are positive for KIT by immunohistochemical analysis on surgical specimens, we have observed several cases of GIST that were negative for KIT on the cell block but subsequently positive on the surgical resection. DOG1 has been found to be a specific and sensitive marker for GISTs on surgical material. We compared KIT and DOG1 staining in 52 GIST cell blocks and in 44 cell blocks of other intra-abdominal spindle cell neoplasms. We found that DOG1 was the more sensitive marker, with positivity in all 52 GIST cell blocks. KIT was positive in 46 (88%) of the GIST cases, with sensitivity dependent on the FNA method. Both markers were highly specific: KIT was negative in all 44 non-GIST cases, whereas DOG1 showed weak positivity in only 1 leiomyosarcoma.

Diagnostic findings of ultrasound-guided fine-needle aspiration cytology for gastrointestinal stromal tumors: proposal of a combined cytology with newly defined features and histology diagnosis

Recently, endoscopic ultrasonography-guided fine needle aspiration (EUS-FNA) has been applied for diagnosis of gastrointestinal submucosal tumors. There have been no definite criteria, however, for the adequate cytological diagnosis of gastrointestinal stromal tumor (GIST) in practice. To facilitate this a novel method is proposed that combines cytology and histology. For 49 cases of submucosal tumor of gastrointestinal tract, EUS-FNA was performed. The aspirated materials were processed for cytology and histology. Both cytological and histological findings were examined on immunocytochemical and immunohistochemical staining of c-kit. Of 49 cases, 40 (81.6%) proved adequate for cytological and/or histological examination. On cytology, cluster types were classified into type A (piled clusters with high cellularity showing a fascicular pattern), type B (thin layered clusters with high cellularity showing a fascicular pattern), and type C (mono-layered clusters or scattered cells). Types A and B were strongly associated with histological diagnosis of GIST. Type C clusters needed confirmation on c-kit positivity and histology. Thus, the combined cytology with newly defined features, and classification and histological diagnostic method for EUS-FNA materials can contribute to improved routine diagnosis for GIST.

Over-expression of c-kit in a primary leiomyosarcoma of the thyroid gland

Primary leiomyosarcoma of the thyroid gland is rare. In this paper, we report a case of high-grade leiomyosarcoma of the thyroid gland in a 43-year-old man. Lung metastasis was also noted in this patient. Despite of aggressive surgical treatment, the patient died of uncontrolled local recurrent disease 6 months after the initial operation. Immunohistochemical studies showed the tumor cells were positive for c-kit proto-oncogene product. Imatinib mesylate was used as a post-operative adjuvant treatment but the response was poor. The role of tyrosine kinase inhibitors on the treatment of thyroid leiomyosarcomas is still unclear because this is the first report of c-kit over-expression in such tumors. Nevertheless, our results show that c-kit over-expression might not be an indicator of good response to imatinib mesylate treatment in thyroid leiomyosarcomas.

Imaging, morphologic, and immunohistochemical correlation in gastrointestinal stromal tumors

BACKGROUND

Gastrointestinal stromal tumors (GISTs) recently have been distinguished morphologically, immunohistochemically, and genetically from other gastrointestinal-tract spindle cell neoplasms. The objective of this study was to correlate clinical and imaging findings with morphology and immunohistochemistry to diagnose GISTs and to differentiate them from other spindle cell lesions in the gastrointestinal tract.

METHODS

The authors reviewed 9 patients who had tumors that were diagnosed as GIST by image-guided and endosonographic-guided fine-needle aspiration (FNA) with or without core biopsy (7 stomach tumors and 2 intraabdominal tumors). The male:female ratio was 3:6, and the patients ranged in age from 38 years to 80 years. Onsite evaluation, preliminary cytologic evaluation, and immunohistochemistry were provided for 6 patients. Immunostains were performed, depending on sample size, on aspirates and/or core biopsies.

RESULTS

On imaging studies, most tumors were smooth and homogenous, consistent with GIST. Tumors ranged in size from 1.8 cm to 22 cm. The largest neoplasm showed solid/cystic and necrotic components. Aspirates consisted of spindle cell, neoplastic proliferation arranged in fascicles that exhibited focal, nuclear palisading; indistinct, cytoplasmic borders; and no significant atypia or mitosis. Focal epithelioid changes or cytologic atypia and mitoses were observed in 2 tumors. Immunostains revealed tumor expression of CD117 and/or CD34 in 5 of 6 tumors, expression of actin in 3 of 6 tumors, and expression of desmin in 1 of 6 tumors. All tumors were diagnosed as GIST (or consistent with GIST for tumors that lacked immunochemical analysis). Five patients underwent surgical excision, and the GIST diagnosis was confirmed in 3 patients, whereas 1 tumor proved to be neurofibroma, and another tumor was leiomyoma. No surgical follow-up was available for the remaining 4 patients, who had imaging and morphologic findings consistent with GIST.

CONCLUSIONS

In the setting of consistent clinical and radiologic findings, the combined use of cytomorphology and immunohistochemistry on FNA and/or core biopsy in most instances provides a reliable pathologic diagnosis of GIST. The need of sufficient material for performing ancillary studies and the usual impossibility of excluding malignancy are limitations of FNA cytology of GIST.

The utility of fine-needle aspiration in the diagnosis of gastrointestinal stromal tumors: a cytomorphologic and immunohistochemical analysis with emphasis on malignant tumors

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the tubular gut and mesentery. Fine-needle aspiration biopsy (FNAB) currently is a useful tool in the diagnosis of GIST because of various mutations of the KIT protooncogene that are recognized as characteristic of these tumors. Despite such advances, the malignant potential of GIST remains variable, and few studies have reported their findings in patients with malignant GIST. Therefore, in the current study, the authors have reported their experience with FNAB as a diagnostic tool in one of the largest series of malignant GISTs and have analyzed the cytomorphologic features of the tumors relative to their clinical behavior to determine which, if any, cytologic features are indicators of malignancy.

METHODS

All patients with histologically confirmed GIST who were diagnosed by image-guided FNAB and confirmed with positive CD117 staining from 1998 to 2003 were included in the study. All tumors were reviewed for various cytomorphologic features. For study purposes, the patients were divided into two groups: Group A included all patients with malignant tumors, defined as those with metastatic disease or recurrent disease after adequate surgery with or without chemotherapy; Group B included all other patients.

RESULTS

In total, 26 tumors from 23 patients (8 males and 15 females) with a mean age of 60.9 years were available for review. There were 14 primary tumors, 7 metastases (to the liver), and 5 recurrences. Twenty-one tumors were unequivocally malignant and were placed into Group A; the remaining 5 tumors were placed into Group B. The tumors in both groups were characterized by spindled or epithelioid cells with minimal nuclear atypia or pleomorphism and a moderate amount of cytoplasm. None of the cytologic features that were evaluated could distinguish reliably between benign tumors and malignant tumors, as expected. However, on cytologic examination, all tumors that demonstrated mitoses (n = 7 tumors) and/or pretreatment necrosis (n = 3 tumors) were identified as malignant.

CONCLUSIONS

FNAB remains a reliable method for the diagnosis of GIST. Immunohistochemical staining of cytologic material with CD117 has been reliable in establishing this diagnosis by FNAB, provided adequate tissue is procured. In the current study, the presence of necrosis or mitoses in cytologic specimens was correlated with a diagnosis of malignant GIST.

Fine needle aspiration biopsy of gastrointestinal stromal tumor presenting as an umbilical mass (Sister Mary Joseph's Nodule)

The Sister Mary Joseph (SMJ) nodule is a clinical sign of metastatic cancer involving the umbilicus. The vast majority of these instances represent adenocarcinomas arising from ovarian or colorectal primaries. We present a patient who presented with ascites and the SMJ lesion that turned out to be a metastatic gastrointestinal stromal tumor after fine needle aspiration biopsy was performed. The lesion was subsequently histologically confirmed. Gastrointestinal stroma tumor involving the umbilicus is exceedingly uncommon and only rarely presents in this fashion. The cytomorphological features, differential diagnosis, and comparison with the tissue specimen are made.

Gastrointestinal stromal tumours: an update

Recently, there has been intense interest in the study of gastrointestinal stromal tumour (GIST); one might call it a virtual GIST revolution. This is due largely to the realization that most GISTs express KIT and harbour activating c-KIT (KIT) or platelet-derived growth factor receptor-alpha (PDGFRA) receptor tyrosine kinase mutations that can be targeted by small molecule pharmacological inhibitors. Pathologists have benefited greatly from this revolution, mainly in the form of an improved ability to classify GISTs and, even more recently, in understanding the molecular underpinnings that underlie many fascinating clinical and pathological correlations. It is the purpose of this review to summarize recent developments in GIST classification and the molecular pathogenesis of GIST.

Endoscopic ultrasound-guided fine-needle aspiration cytology for diagnosis above and below the diaphragm

Endosonography ultrasound (EUS) is a minimally invasive technology using a high-frequency ultrasound transducer that is incorporated into the tip of a conventional endoscope. This technique permits high-resolution imaging of the gastrointestinal wall and structures in its vicinity, as well as real-time endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA). This is a review of the literature on EUS-guided FNA of the mediastinal and abdominal lymph nodes, the pancreas, intramural gastrointestinal masses, and other miscellaneous organs and body cavities. EUS-guided FNA is a recently developed procedure that has established itself as a safe, highly accurate, and clinically useful modality.

c-KIT mutation analysis for diagnosis of gastrointestinal stromal tumors in fine needle aspiration specimens

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are a specific clinicopathologic entity characterized by activating mutations in the c-KIT gene. These mutations are associated with increased immunohistochemical staining for the c-KIT protein. Because many GISTs display a definitive response to the KIT inhibitor imatinib, accurate diagnosis of these neoplasms is of great clinical importance. GISTs are the most common mesenchymal neoplasms of the digestive tract and show lineage differentiation along the lines of the interstitial cells of Cajal. The cytomorphology of GISTs has been well described, but the cytologic features are not entirely specific and immunohistochemical staining is frequently used to confirm the diagnosis. However, KIT protein positivity established by immunohistochemistry (IHC) may be unreliable in some instances because of a small number of KIT-negative GISTs and immunohistochemical KIT positivity in some non-GIST spindle cell neoplasms of the gastrointestinal tract. Antigen retrieval may be the cause of this spurious positivity. Recently, the demonstration of KIT and PDGFRA mutations has been shown to be more reliable in establishing the diagnosis of GIST than IHC.

METHODS

High resolution amplicon melting analysis was performed in a series of eight gastrointestinal stromal tumors sampled by fine needle aspiration (FNA).

RESULTS

In five of eight cases, adequate material was obtained for mutational analysis. In four of these, mutations in the c-KIT gene were detected, and in the fifth case a mutation in the PDGFRA gene was detected.

CONCLUSIONS

It appears that high resolution amplicon melting analysis can be successfully performed on material obtained by FNA and will show either KIT for PDGFR mutations in the majority of GIST FNA specimens.

Pitfalls in endoscopic ultrasound-guided fine-needle aspiration and how to avoid them

Although a broad range of pancreatic, gastrointestinal, thoracic, and abdominal pathology may be sampled by endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA), certain difficulties tend to recur because of the frequency of certain sample types and because of the nature of their individual cytomorphologic profiles. With this in mind, we review certain pitfalls that may befall cytopathologists with EUS-guided FNA. We discuss the diagnosis of pancreatic ductal adenocarcinoma and of other pancreatic epithelioid tumors including pancreatic endocrine neoplasms, solid pseudopapillary tumors, and acinar cell carcinomas. We also discuss the diagnosis of pancreatic cystic neoplasia including intraductal papillary mucinous neoplasms and mucinous cystic neoplasms and the diagnosis of gastrointestinal mesenchymal neoplasia with particular attention to gastrointestinal stromal tumors. Finally, we discuss the interpretation of lymph node aspirates.

Submucosal lesions

Most of the submucosal lesions encountered on endoscopy are benign; however, the fact that some of them may be malignant considerably influences the attitude toward the whole group. This article reviews the current status of endosonography in the management of submucosal lesions and focuses on determining the risk of malignancy. The predictive value of various endoscopic ultrasonography (EUS) features and their combinations and the capabilities and limitations of EUS-guided fine needle biopsy are discussed. Other issues addressed include differentiation between extraluminal compressions and true submucosal lesions, EUS-assisted endoscopic removal of submucosal lesions, and the potential role of catheter-based endosonography in the setting of submucosal lesions. Problems related to the surveillance of patients with submucosal lesions who are not candidates for surgical treatment are outlined. An overview of the recent changes in the pathologic classification of gastrointestinal mesenchymal tumors and their impact on the role of EUS in the management of submucosal lesions is given.

Endoscopic sonographically guided fine-needle aspiration yield in submucosal tumors of the gastrointestinal tract

OBJECTIVE

To study the yield of endoscopic ultrasonographically guided fine-needle aspiration cytologic examination in the diagnosis of submucosal masses.

METHODS

From 1999 to 2003, 10 patients underwent ultrasonographically guided fine-needle aspiration for the cytologic diagnosis of submucosal masses in our institution. The endoscopic ultrasonography records and the cytology database were consulted, and the reports were analyzed, as were slide material and the technical aspects related to these procedures. All procedures were performed under conscious sedation and cardiorespiratory monitoring on an outpatient basis. Ten patients (4 men and 6 women; mean age, 60.8 years) were studied.

RESULTS

Eight lesions were located in the stomach, and 2 were located in the esophagus, with a mean diameter of 3.3 cm. An experienced cytopathologist was present on-site during all procedures for assessment of adequacy and preliminary cytologic examination. Cytologic diagnoses were obtained in 8 cases as follows: 6 gastrointestinal stromal tumors, 1 organizing submucosal hematoma, and 1 low-grade mucosa-associated lymphoid tissue-associated lymphoma. Two cases consisted of scant gastric epithelium only and were considered nondiagnostic. The cytologic diagnoses guided further clinical treatment.

CONCLUSIONS

Ultrasonographically guided fine-needle aspiration with cytopathologic analysis has a high accuracy rate (80%) for diagnosing submucosal lesions. These findings potentially affect clinical decision making.

Differential diagnosis of gastrointestinal stromal tumor and other spindle cell tumors in the gastrointestinal tract based on immunohistochemical analysis

To confirm the usefulness of an immunohistochemical panel of antibodies for KIT (c-kit/CD117), CD34, desmin, smooth-muscle actin (SMA), h-caldesmon (HCD), S-100 protein, neuron-specific enolase (NSE), and beta-catenin, 297 mesenchymal and peripheral nerve-sheath tumors of the gastrointestinal tract and intra-abdominal locations including 211 gastrointestinal stromal tumors (GISTs), 12 leiomyomas, 18 leiomyosarcomas, 17 solitary fibrous tumors (SFTs), 14 schwannomas, and 25 desmoid-type fibromatoses (DTFs) were analyzed immunohistochemically. Consistent (100%) immunoreactivity for KIT, CD34, desmin and S-100, and nuclear accumulation of beta-catenin were detected in GISTs, SFTs, smooth-muscle tumors, schwannomas, and DTFs, respectively. Immunoreactivity for SMA, HCD, and NSE was observed in a wide range of these tumors. In addition, 418 bone and soft tissue tumors were enrolled in this study for KIT immunostaining. As a result, a limited number of these tumors were KIT positive, including synovial sarcoma that showed morphological similarity to GISTs. These findings suggest that KIT, CD34, desmin, S-100, and beta-catenin are key markers for clinical diagnosis of GISTs and other spindle cell tumors that may involve the gastrointestinal tract, whereas SMA, HCD, and NSE have only limited value.

Endoscopic ultrasound-guided fine-needle aspiration cytology of peripheral nerve-sheath tumors

Endoscopic ultrasound (EUS) has allowed for the fine-needle aspiration and diagnosis of many different gastrointestinal neoplasms, including mesenchymal tumors. Although most mesenchymal tumors of the gastrointestinal tract are gastrointestinal stromal tumors (GISTs), other mesenchymal tumors, including neural tumors, do occur. Proper diagnosis and differentiation of these tumors from GISTs are important because of their different prognoses and treatment regimens. We encountered three peripheral nerve-sheath tumors of the gastrointestinal tract aspirated by EUS (two schwannomas and a granular-cell tumor). We report on the endoscopic ultrasound, cytologic, histologic, and immunohistochemical findings of these cases.

Gastrointestinal tract cytology: advancing horizons

Tide and ebb of interest in gastrointestinal tract cytology has followed technical advances in this field over the last 60 years. Cytologic samples can be obtained using gastric lavage, abrasive balloons, mucosal brushing, and fine needle aspiration (under percutaneous image guidance, endoscope and endoscopic ultrasound guidance). These advances now allow simultaneous performance of brushing the abnormal mucosa, obtaining fine needle aspirates and excising mucosal biopsy samples for evaluation. Use of endoscopic ultrasound guided fine needle aspirates now help to obtain diagnosis of submucosal lesions, preoperative staging of gastrointestinal tract malignancies and help determine further management of patients. Such advances have brought pathologists to the forefront of the patient management team for the treatment of gastrointestinal tract lesions. This manuscript reviews the advantages and limitations of each cytology associated technique as well as reviews the salient diagnostic features, differential diagnosis and diagnostic pitfalls of gastrointestinal tract lesions. Finally, it suggests the modalities best suited to obtain diagnosis for various gastrointestinal tract lesions.

Epithelioid variant of gastrointestinal stromal tumor: Diagnosis by fine-needle aspiration

Epithelioid gastrointestinal stromal tumors (GISTs) may cause significant diagnostic confusion on fine-needle aspiration (FNA) with carcinomas, neuroendocrine tumors, and melanoma, particularly when metastatic. This study characterizes the cytologic features of nine cases of epithelioid GISTs that were obtained by computerized tomographic guidance in five, by endoscopic ultrasound in three, and from an excised liver tumor in one. Six cases presented as liver masses, one as a perisplenic mass, one as an abdominal mass, and one as a gastric mass. The aspirates revealed mainly single or small clusters of epithelioid cells with a moderate amount of granular to clear cytoplasm, small uniform nuclei with mild to marked nuclear envelope irregularities. Binucleation and intranuclear inclusions were frequent findings. Collagenous stroma was seen in most cases. In three cases, a neuroendocrine tumor was the initial diagnosis. Immunocytochemical staining for c-kit (CD117) was performed on cellblocks in six cases and was positive in five cases. On the subsequent surgical specimen, CD117 was positive in the c-kit-negative cytology case. The diagnosis of GIST should be considered in aspirates of the gastrointestinal tract, liver, mesentery, or abdominal wall mass lesions when epithelioid cells are the predominant cell type. Ancillary studies such as immunohistochemical stains are usually helpful in making a definitive diagnosis.

Fine-needle aspiration cytology and immunocytochemistry in the diagnosis of 24 gastrointestinal stromal tumors: a quick, reliable diagnostic method

The diagnosis of gastrointestinal stromal tumors (GISTs) is generally established on histopathologic examination of surgical specimens. Fine-needle aspiration (FNA), performed under the guidance of ultrasound or computed tomography, is being used with increasing frequency in an attempt to diagnose primary and/or metastatic GISTs before surgery. The present study was undertaken to characterize the cytological appearance of these tumors and to assess the role of cytology, together with immunocytochemistry (ICC), in the diagnosis of GISTs. Twenty-four GISTs diagnosed by FNA cytology at our institution have been reviewed. Immunocytochemical studies with c-kit and CD34 were performed in all cases on current or archival Papanicolaou-stained smears. All cases stained with c-kit, and 19 reacted with CD34. Cytomorphology and immunocytochemical characteristics are discussed. Our results confirm the utility of FNA together with ICC in the diagnosis of primary and/or metastatic GISTs.

Fine-needle aspiration cytology diagnosis of metastatic gastrointestinal stromal tumor in the liver: a report of three cases

Gastrointestinal stromal tumor (GIST) is the designation for a major subset of gastrointestinal mesenchymal tumors that histologically, immunocytochemically, and genetically differ from leiomyomas, leiomyosarcomas, and schwannomas. GISTs derive from the interstitial cells of Cajal and, in addition to variable expression of smooth muscle and neural markers, they characteristically express CD34 and CD117. The cytological appearance, including immunocytochemical and mutational analysis of c-kit gene in primary GIST has been well described. To our knowledge, only two cases of metastatic GIST diagnosed by fine-needle aspiration (FNA) have been reported. We illustrate three cases of metastatic GIST in the liver. Two cases had no prior history of gastrointestinal tumor and the third case had a 4-yr previous history of duodenal tumor. Consistent immunocytochemistry and ultrastructual studies supported the diagnosis of GIST. We emphasize that in the appropriate clinical and radiological setting, a confident diagnosis of GIST can be established by FNA of metastatic lesions.

Management of malignant gastrointestinal stromal tumours

Gastrointestinal stromal tumours (GISTs) are the most common form of mesenchymal tumour of the gastrointestinal tract. Clinically, they range from small indolent tumours curable with surgery alone to aggressive cancers. Making a distinction between an indolent and a malignant GIST is unreliable with conventional histopathological techniques. The presence of metastases at the time of diagnosis confirms malignancy, but all GISTs should be regarded as having malignant potential. GISTs characteristically express the KIT protein, a transmembrane tyrosine kinase receptor for stem-cell factor. Most GISTs have a mutation in the KIT proto-oncogene that translates into a gain-of-function constitutive activation of the KIT kinase. KIT activation seems to be an early tumour-promoting event in pathogenesis. Commonly, malignant GISTs show high-level primary resistance to conventional chemotherapy. Imatinib mesylate is an orally administered selective inhibitor of certain tyrosine kinases including KIT. Most patients with advanced malignant GISTs achieve clinical benefit and significant antitumour responses with imatinib mesylate. Responses have been durable, and most patients tolerate the drug well at clinically effective doses. Imatinib mesylate is the first effective systemic therapy for advanced GIST.