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Year : 2015  |  Volume : 58  |  Issue : 4  |  Page : 448-452
Cytologic diagnosis of gastric submucosal lesions by endoscopic ultrasound-guided fine-needle aspiration: A single center experience in Saudi Arabia

1 Division of Pathology, King Khalid University Hospital, King Saud University, Riyadh; Division of Pathology, Alfaisal University, Riyadh, Saudi Arabia
2 Division of Gastroenterology, King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia; Division of Gastroenterology, The McGill University Health Center, Montreal General Hospital, McGill University, Montreal, Canada
3 Division of Gastroenterology, King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia
4 Division of Surgery, King Khalid University Hospital, Riyadh, Saudi Arabia

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Date of Web Publication4-Nov-2015


Background and Aims: Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) sampling has become standard practice for the diagnosis of submucosal gastrointestinal (GI) lesions. The aim of this study was to determine the utility of EUS-guided FNA cytology in the diagnosis of deeply seated gastric mass lesions. Materials and Methods: Thirteen patients with deeply seated gastric mass lesions were diagnosed by EUS-FNA. Adequate cytology material was present in all cases. Cell blocks were available in 10 cases. Surgical resections were performed in 8 cases. Immunohistochemical (IHC) studies were done on cell blocks in 9 cases and on 6 resected specimens. Seven cases has proved to be GI stromal tumors (GIST), in four of them, cell blocks were available, and resection for GIST was performed in 5 cases. IHC stains that were performed in cytology, as well as resection specimens, revealed similar results in each patient. Conclusion: EUS-FNA cytology, when combined with a histologic assessment of cell blocks provides accurate and efficient tissue diagnosis of a wide variety of deeply seated gastric mass lesions.

Keywords: Deeply seated gastric mass lesions, endoscopic ultrasound-guided, fine-needle aspiration, gastrointestinal stromal tumor

How to cite this article:
Raddaoui E, Almadi MA, Aljebreen AM, Alsaif F. Cytologic diagnosis of gastric submucosal lesions by endoscopic ultrasound-guided fine-needle aspiration: A single center experience in Saudi Arabia. Indian J Pathol Microbiol 2015;58:448-52

How to cite this URL:
Raddaoui E, Almadi MA, Aljebreen AM, Alsaif F. Cytologic diagnosis of gastric submucosal lesions by endoscopic ultrasound-guided fine-needle aspiration: A single center experience in Saudi Arabia. Indian J Pathol Microbiol [serial online] 2015 [cited 2021 May 16];58:448-52. Available from: https://www.ijpmonline.org/text.asp?2015/58/4/448/168868

   Introduction Top

Before introducing endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) biopsy, most of the deeply seated gastric mass lesions, which include submucosal, intramural, and subserosal lesions were evaluated and diagnosed by surgical resection. Because of their deep location, endoscopic biopsies did not usually yield diagnostic material in the majority of cases.

A large part of these deeply seated lesions would turn out to be gastrointestinal stromal tumors (GIST). GIST encompasses a heterogeneous group of mesenchymal tumors of the gastrointestinal (GI) tract originating mostly from the wall of the stomach and intestines and occasionally in other sites such as the mesentery and the omentum.[1]

Upon reviewing the literature for deeply seated gastric lesions, only a few case reports and a small series of cases have addressed the value of cytologic specimens retrieved by either computed tomography (CT)-guided FNA or intraopearative FNA.[2],[3],[4],[5]

The early and accurate diagnosis of these rare lesions affects the patient management and facilitates the possibility of optimal surgical resection, which may reduce the number of nonresectable or metastatic cases. Currently, EUS-FNA has been considered as an accepted and commonly practiced tool for the evaluation of different types of deeply seated GI lesions [6],[7],[8] with more cases, especially of GIST tumors sampled by this technique.[6],[7],[8],[9],[10]

EUS-FNA cytology has been proven cost effective and accurate for the diagnosis of other GI tract organs such as the pancreas.[11] The efficiency of this procedure has not been confirmed with the deeply seated gastric lesions. The current study aimed to evaluate the local experience and accuracy of EUS-FNA in the diagnosis of deeply seated gastric lesions and to describe the cytomorphologic findings of such lesions.

   Materials and Methods Top

Thirteen patients with deep gastric mass lesions were diagnosed by EUS-guided FNA cytology, from October 2010 to June 2014.

In our institution, we do not perform EUS-FNA when the submucosal lesion is <2 cm. For lesions more than 5 cm in size and when the features are classical for diagnosis of a GIST, patients are usually referred to surgery unless preoperative imatinib therapy followed by FNA are planned. For lesions with a size between 2 and 5 cm patients are followed by EUS, and EUS-FNA is performed, if there are changes in size or sonographic features when compared with baseline EUS. If the submucosal lesion had features that are not classical for GIST, an FNA is usually performed.

All EUS procedures were performed by one of two experienced gastroenterologists. These patients were either referred from other local gastroenterologists or from outside institutions following a diagnosis of a submucosal lesion that was either identified by gastroscopy or computed cross-sectional imaging. After a written informed consent was obtained, all patients underwent EUS examination of the submucosal lesion under conscious sedation. EUS was performed using a linear echoendoscope. A dedicated ultrasound scanner (ALOKA SSD-Alpha 10, ALOKA Ultrasound System, Japan) was used for image processing. If the endoscopist decided to perform an FNA of the submucosal lesion, a 21 or 25 gauge needle EUS needle was used based on the discretion of the endoscopist. Smears were made at the bedside in the endoscopy suite with the availability of an on-site cytotechnologist in order to assess sample adequacy.

Thirteen patients with deep gastric mass lesions were diagnosed by EUS-guided FNA cytology, from October 2010 to November 2013, at the King Khalid University Hospital (KKUH), King Saud University, Riyadh, Saudi Arabia. All smears were prepared on-site at the endoscopy unit.

Preparation of smears

The aspirated material was expelled on glass slides by the operating endoscopist and smeared by a cytotechnologist. Two to four slides were prepared from each pass, taking care that any clotted material was preserved for cell block. Air dried (for Diff-Quick staining) and fixed smears (fixed immediately in 95% ethyl alcohol for subsequent Papanicolaou staining) were prepared in an almost equal ratio with slightly more emphasis on fixed smears. Pass number (indicating a specific site of collection) was marked on each slide, and the site of collection of each pass was noted on a separate paper. One or two representatives air dried smears from each pass were immediately stained with rapid Romanosky (Diff-Quick stain from Shandon Corp.,) and examined under the microscope in order to assess specimen adequacy, give preliminary diagnostic interpretation if necessary, and to suggest additional studies if indicated. Additional material was collected for ancillary studies if necessary (in cases of lymphomas, tuberculosis, etc.,) and preserved in normal saline (for Microbiology) or RPMI cell preservative solution (for Flow-Cytometry), if and as required. RPMI cell preservative solution was used as a cell collection/preservation and transport medium for cell block, and subsequent ThinPrep slides preparation. The material collected for cell block was grossly examined before the end of the procedure, and if the collected material was not sufficient to make a good cell block, an additional pass was dedicated to cell block only.

Preparation of ThinPrep slides

RPMI needle wash was centrifuged immediately, and an aliquot was separated for ThinPrep processing and processed on ThinPrep 2000 machine, according to the manufacturer's instructions (ThinPrep processing manual).

Preparation of cell block

The remaining sediment including any clotted material was fixed immediately in cell block fixative (10% Alcohol formalin), centrifuged, and the material transferred to a histology embedding cassette, and processed for routine histologic examination using standard techniques. Seven patients subsequently underwent surgical resections at KKUH. Histologic sections (5 microns) were cut from formalin-fixed and paraffin-embedded tissue blocks, and stained with H and E. Appropriate immunohistochemical (IHC) studies were performed on cell blocks and surgical specimens. For this purpose, 5-micron sections were cut, deparaffinized and mounted on precoated slides. As we needed, CD117 (c-kit), CD34, smooth muscle actin (SMA), S-100 protein, Desmin, Vimentin, Synaptophysin, and CK-AE1/AE3 immunostaining was performed using an automatic stainer (Biotek 500, Ventana).

The final reaction product was visualized with diaminobenzidine. Positive as well as negative control slides obtained from normal or tumor tissue known to express the tested antigens CD117 (c-kit), CD34, SMA, Desmin, Vimentin, CK-AE1/AE3, Synaptophysin and S-100 protein were included routinely in the IHC assays. Sections were counterstained with hematoxylin (Ventana). [Table 1] lists the sources and working dilutions of the antibodies used in this study. All cytology slides and histology sections were examined by an experienced cytopathologist.
Table 1: Antibodies used for immunohistochemical studies

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   Results Top

The mean age of patients was 56.8 years (range, 43–82 years). Seven patients were females and six were males. The tumors were all located deeply in the stomach wall: Three submucosal, seven intramural within the muscularis propria, and three subserosal. The mean size of the tumors documented by EUS was 7.5 cm (range 1.5–30 cm). The final cytopathologic and histopathologic diagnosis in the 13 cases are included [Table 2]. Nine cases showed spindle cell lesions, seven proved to be GIST by IHC that was done on cell blocks in 4 cases and on follow-up resection samples in 5 cases. One highly malignant spindle cell lesion proved to be a high-grade sarcoma on both cytology and histology resection. IHC was performed on both the cell block and the excised specimens. One benign appearing spindle cell lesion proved to be leiomyoma by IHC. One case showed benign epithelial cell clusters, and follow-up resection confirmed the diagnosis of pancreatic heterotopia. One case showed benign and mature adipose tissue consistent with lipoma. One case showed malignant epithelial cell clusters, IHC confirmed the diagnosis of metastatic carcinoma, which was consistent with the patient's previous history of ovarian serous carcinoma.
Table 2: Final diagnosis and distribution of cases

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Smears of GIST tumors showed the highly cellular material with spindle cell morphology [Figure 1]. Low magnifications showed both tight aggregates and loosely cohesive spindle cells with the unremarkable background. The high-power view revealed that the tumor cells were mostly well-organized in one direction with ill-defined cytoplasmic borders. The nuclei were a spindle or oval shaped with smooth and thin membranes and inconspicuous nucleoli. Focal palisading was observed in some cases. Smears of high-grade sarcoma revealed frankly malignant spindle cell neoplasm with nuclear pleomorphism, necrosis, and frequent mitosis [Figure 2]. Smears of the smooth muscle neoplasm namely leiomyoma showed bundles of bland looking, uniform spindle cells with cigar-shaped nuclei and eosinophilic, ill-defined cytoplasm with no evidence of mitoses or necrosis [Figure 3]. Smears of the pancreatic heterotopia revealed tightly cohesive clusters of benign looking epithelial cells with uniform, mid-size nuclei, granular cytoplasm, and inconspicuous nucleoli [Figure 4]a. Smears of lipoma showed tightly cohesive clusters of uniform mature fat cells with small, regular nuclei with no evidence of hyperchromasia; and smears of metastatic carcinoma revealed malignant; three-dimensional clusters of epithelial cells with enlarged, irregular shaped, vesicular nuclei, and prominent nucleoli [Figure 5]. Cell blocks were available in 10 cases, and contained diagnostic material in 8 cases; IHC stains were done on cell blocks that had adequate material and the findings [Table 3] were characteristic and confirmed the diagnosis of four GIST tumors, one high-grade sarcoma, one leiomyoma, and one metastatic carcinoma. Surgical resections were performed in eight patients; in five of them the diagnosis of GIST tumors was confirmed histologically and by IHC findings (in all cases tumor cells were positive for Vimentin, CD117, and CD34, and negative for all other markers). Resection also confirmed histologically and by IHC results the diagnosis of high-grade sarcoma. A surgical specimen of pancreatic heterotopia showed on H and E stain sections the typical and characteristic mixture of benign pancreatic ductal, acinar, and neuroendocrine elements (Islets of Langerhan's) [Figure 4]b. Resection specimen of lipoma showed submucosal, well demarcated, 10 cm in size fatty tissue mass. H and E stain sections revealed lobulated, benign, fully matured adipose tissue. Neither nuclear atypia nor lipoblasts were seen. Two GIST tumors were categorized as benign GIST based on the tumor size (<5 cm) and very low mitotic counts (<1/50 high-power field). Two GIST tumors were categorized as intermediate malignant potential, and one GIST tumor was categorized as malignant based on size and high mitotic index. The results of the IHC analysis in two surgical specimens were identical to those in the corresponding cell blocks.
Figure 1: Gastrointestinal stromal tumors, smears revealed tight aggregates of tumor cells with a clean background nuclei are streaming in one direction, (Papanicolau stain, original magnification ×400)

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Figure 2: High-grade sarcoma, cell block revealed spindle cell neoplasm with hyperchromatic, pleomorphic nuclei, and frequent mitosis (arrows), (H and E stain, original magnification ×400)

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Figure 3: Leiomyoma, smear, tumor cells have ill-defined cytoplasmic border, uniform, long spindle nuclei with smooth nuclear membrane, finely distributed even chromatin and inconspicuous nucleoli, (Papanicolau stain, original magnification ×500)

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Figure 4: (a) Pancreatic heterotopia, cytology smears showed tightly cohesive clusters of uniform, bland appearing epithelial cells with granular cytoplasm and oval nuclei, (Diff-Quick stain, original magnification × 400). (b) Resection specimen, high-power view showed mixture of benign pancreatic acini (long arrows) and ducts (short arrows), (H and E stain, original magnification ×400)

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Figure 5: Metastatic adenocarcinoma, smears showed three-dimensional clusters of malignant epithelial cells with large vesicular nuclei and macro nucleoli, (Papanicolau stain, original magnification ×500)

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Table 3: Results of IHC Studies

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   Discussion Top

Deep-seated gastric wall mass lesions are uncommonly seen in clinical practice. The differential diagnosis includes benign and malignant neoplasms, as well as nonneoplastic lesions.[1],[12]

The neoplastic lesions are predominantly mesenchymal and epithelial in origin. Mesenchymal lesions include mainly GIST tumors, smooth muscle tumors, peripheral neurogenic tumors, and rarely others. Epithelial neoplastic lesions include both primary and secondary metastatic carcinomas. Benign, nonneoplastic processes can rarely involve the deeper part of the gastric wall. Examples include benign pancreatic heterotopias, inflammatory processes, and others. Few previous studies are available on submucosal, and intramural gastric lesions and those have been limited by small patient numbers, lack of standardized criteria, and the limited spectrum of lesions.[1],[2],[4],[5],[6],[7],[13],[14]

Although GIST tumors are uncommon neoplasms, they constitute the largest group of mesenchymal tumors in the GI tract. These tumors arise from the wall of the stomach, intestines, rectum, and occasionally the mesentery and omentum. They were previously classified as smooth muscle tumors and schwannomas. Currently, it has become widely accepted that the cell of origin of GIST is the interstitial pacemaker cells of Cajal,[15],[16] and these cells are consistently positive for CD34[15],[16] and/or CD117 (c-kit).[17]

Most of the reported cytologic studies on the gastric mass lesions have been done on lavage, washing, or brushing technique through endoscopy.[18]

The application of CT-guided percutaneous FNA in GI tract lesions, in general, has been limited in spite of the use of this technique in other organs such as the pancreas, liver, kidney, and other organs. Recently, EUS-guided FNA has been proved to be an efficient tool in the evaluation of deeply seated, unreachable GI lesions.[19],[20],[21] EUS-FNA is cost-effective, less invasive, and highly sensitive and specific. It can be used both for diagnosis and staging purposes of various upper GI diseases. Matsui et al.[14] has shown in a study of 29 submucosal cases that EUS-FNA increased the diagnostic capability of EUS in differentiating between the various types of submucosal tumors of the upper GI tract. This study did not, however, include cytologic findings or IHC testing results.

Ando et al.[22] reviewed 49 submucosal GISTs, with 91.8% adequate samples. Twenty-three lesions were surgically resected (20 were GISTs), and their accuracy rate was 95%. Our study showed that preoperative FNA could help to obtain the correct diagnosis of deeply seated gastric lesions, benign or malignant, epithelial, or mesenchymal, whenever both cytology smears and cell blocks were obtained by the EUS-FNA procedure. This highlights the importance of the on-site evaluation of cytology material adequacy at the time, when the procedure is performed. On-site evaluation helps the cytotech/pathologist to request more material when necessary in order to obtain enough cells to enable additional studies on cell block preparations.

   Summary Top

Utilizing EUS-guided FNA in the evaluation of deeply seated, unreachable gastric wall lesions could achieve, when properly operated an adequate, and diagnostic cellular material. Such lesions can be accurately and efficiently diagnosed by EUS-guided FNA when cytology smears are combined with cell blocks which enable confirmation by IHC studies. Finally, there was clear concordance between the IHC results of both cell block preparations that were obtained by EUS-FNA, and the results obtained from the follow-up surgical resections.

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Conflicts of interest

There are no conflicts of interest.

   References Top

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Correspondence Address:
Dr. Emad Raddaoui
Division of Pathology, King Khalid University Hospital, College of Medicine, King Saud University, P.O. Box 2925/32, Riyadh 11461
Saudi Arabia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0377-4929.168868

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]

  [Table 1], [Table 2], [Table 3]

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