CYTODIAGNOSIS OF GASTROINTESTINAL STROMAL TUMOURS (GISTs) ON ROMANOWSKY STAINED SMEARS Priyanka Agrawal 1, Subhash Agrawal 2, Atul Gupta 3, Anurag Gupta 4 HOW TO CITE THIS ARTICLE: Priyanka Agrawal, Subhash Agrawal, Atul Gupta, Anurag Gupta. Cytodiagnosis of Gastrointestinal Stromal Tumors (GISTs) on Romanowsky Stained Smears. Journal of Evolution of Medical and Dental Sciences 2014; Vol. 3, Issue 04, January 27; Page: 895-901, DOI: 10.14260/jemds/2014/1921 ABSTRACT: This is a retrospective study on 7 cases diagnosed as GISTs on cytology. It includes 5 (71.5%) cases from stomach, of which 3(43%) were forming exogastric mass & 2 (28.5%) were from colon. Two (28.5%) of 7 cases were reported as spindle cell GISTs (possibly benign). Three (43%) cases were reported as spindle cell GISTs (possibly. Remaining 2 (28.5%) cases were reported as epithelioid GISTs (possibly. Histological correlation was possible in both cases of spindle cell GISTs (possibly benign) and 2 of 3 cases of spindle cell GISTs (possibly. Diagnosis of epithelioid GISTs was also confirmed on histology. All 6 (86%) cases correlated with cytological diagnosis. Cytological features were studied on Romanowsky stained smear. This study illustrates the cytological features and helps the cytopathologist to diagnose these cases. A cytologist should consider the diagnosis of GISTs; both for spindle cell & epithelioid lesions of abdomen. These lesions respond very well to imatinib & do not have very poor prognosis as that of deep seated sarcomas and hepatocellular carcinoma. KEYWORDS: GIST, Cytodiagnosis. MeSH terms: Gastrointestinal stromal tumor, Cytodiagnosis. INTRODUCTION: Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the gastrointestinal tract arising from interstitial cells of Cajal. GISTs are now defined as cellular, spindle cell, epithelioid or occasionally pleomorphic mesenchymal tumors of the GIT expressing CD 117 (ckit), a product of c-kit proto-oncogene and CD34 (usually). 1 They are most common in stomach (60-70%). 2 Larger tumors protrude intraluminally or to the serosal side and may have a massive extragastric component. Pathologic assessment of malignancy is disappointing, even on histology. Aggressive behavior depends on tumor size, mitotic frequency and coagulation necrosis. NIH consensus guidelines for defining risk of aggressive behavior in GISTs at any anatomical site are given in Table 1. 3 Because of the submucosal or intramural location of this tumor, endoscopic biopsy is often ineffective in making a biopsy diagnosis. [2] Ultrasonography (USG) guided, computed tomography (CT) guided or endoscopic ultrasonographically (EUS) guided fine needle aspiration 1, 2, 4,5The cytology (FNAC) is being increasingly used for the diagnosis of these tumors. cytological features of GIST have been documented and few reports have been supported by 1, 2, 4-8 immunocytochemistry (ICC). This work was conducted to study the cytomorphological features of cases cytologically diagnosed as GISTs on Romanowsky stained FNA smears and to identify the problems encountered in cytological interpretation of these aspirates. METHODS: It is a retrospective study of cases diagnosed as GIST in a period of 1 year (Nov2008- Oct2009) on image guided FNAC smear. All tumors were aspirated under ultrasonographic / CT Journal of Evolution of Medical and Dental Sciences/ Volume 3/ Issue 04/January 27, 2014 Page 895
guidance. Aspirations were done with a 22-gauge needle and 20 ml syringe using the standard procedure, and smears were prepared, air-dried and stained with May-Grunwald Giemsa stain. Cytomorphological features were studied and cytodiagnosis was made, which was correlated with histology, wherever possible. Study was performed after approval of ethical committee of hospital which conforms to the norms of the Helsinki declaration on human experimentation (institutional or regional). RESULTS: Seven cases of GISTs were studied. Five (71.5%) were from stomach and 2 (28.5%) from colon. Five (71.5%) patients were male and 2 (28.5%) female, with ages between 34 to 61 years. Two (28.5%) of 7 cases were reported as spindle cell GISTs (possibly benign). Three (43%) cases were reported as spindle cell GISTs (possibly. Remaining 2 (28.5%) cases were reported as epithelioid GISTs (possibly. The age, sex, clinical presentation, radiological findings, cytodiagnosis & histodiagnosis of cases is given in Table-2. Cytological features: Smears of cases diagnosed as spindle cell GISTs (possibly benign) were cellular in hemorrhagic background. Spindle to oval cells with mild pleomorphism were arranged in fascicular & whorling patterns with collagenous stroma (Figure 1). Palisading was also noticed in 1 of 2 cases (Figure 2). Cytoplasm was moderate with ill-defined boundaries. Nucleus was medium sized, oval with blunt ends and had fine granular chromatin. Few stripped nuclei were seen in 1 of 2 cases. Histology of both cases supported the cytodiagnosis (Figure 3). Smears of cases cytologically reported as spindle cell GISTs (possibly were cellular with spindle to oval cells in hemorrhagic background; both loosely clustered & dispersed (Figure 4). Prominent coagulative necrosis was seen in 1 of 3 cases. Cytoplasm was scant to moderate, with some vacuolization & ill-defined borders (Figure 4). Few stripped nuclei were seen. Nuclei were of medium size, oval or cigar-shaped & occasionally spindle or comma shape. Chromatin was granular. Two cases revealed nuclear features as those of benign spindle GIST, while 1 case revealed moderately pleomorphic nuclei with high N: C ratio & rare mitotic figures but nuclear membrane was regular (Figure 5). These cases were labeled possibly malignant on the basis of radiological findings & NIH guidelines, which states that size of more than 10cm is of high risk. Histology of 2 of 3 cases was available which supported the cytodiagnosis. Cytology of epithelioid GISTs (possibly of exogastric mass of 14 cm diameter revealed cellular smears with groups of histiocytes (Figure 6). Round to polygonal, occasionally spindled, medium sized cells with moderate pleomorphism were loosely clustered as well as dispersed (Figure 7). Cytoplasm was abundant & well-defined. Nucleus was medium sized, round, with coarse chromatin & moderate pleomorphism. Nucleoli were not seen. Cytological features were somewhat similar to that of hepatocellular carcinoma but radiological finding was from stomach. Thus, epithelioid GIST was the first differential diagnosis; others were hepatocellular carcinoma, metastatic carcinoma, neuroendocrine tumor & melanoma. Immunocytochemistry could not be performed, due to unavailability. Histology confirmed the cytodiagnosis. Epithelioid GISTs (possibly from colon (16 cm diameter) on cytology revealed cellular smear in hemorrhagic & necrotic background. Medium sized, mildly pleomorphic, predominantly oval with occasional spindle cells were loosely clustered or dispersed singly (Figure 8). Cytoplasm was moderate in amount, with ill-defined borders & some vacuolization. Medium sized Journal of Evolution of Medical and Dental Sciences/ Volume 3/ Issue 04/January 27, 2014 Page 896
oval to comma shaped, mildly pleomorphic nuclei with granular chromatin were noticed (Figure 9). Occasional intranuclear cytoplasmic inclusions & mitosis were seen. A differential diagnosis was also suggested which includes epithelioid GIST, hepatocellular carcinoma, metastatic carcinoma, neuroendocrine tumor & melanoma. Later, histology confirmed the diagnosis of epithelioid GIST. Problem encountered were: 1. Differentiation between benign and malignant GIST (on cytology), 2. Cytological diagnosis of epithelioid GIST. DISCUSSION: Patients of GISTs were between 34 to 61 years, a finding similar to Deshpande et al. 71.5% cases were male & 28.5% female, a finding resembling that of Gu et al. Five (71.5%) were from stomach and 2 (28.5%) from colon, a finding in accordance to Deshpande et al. Cytological findings of spindle cell GIST (possibly benign & possibly were similar to those discussed by Boggino et al, Deshpande et al, Gu et al, Li et al, Dodd et al, Kimura et al and Kwon et al. As given Deshpande et al & Li et al, differentiation between benign and malignant GIST, on cytology is very difficult. We also found that, loose cohesive clusters, nuclear pleomorphism, high N: C ratio, nuclear membrane irregularity, coarse chromatin, necrosis & mitosis favor malignant behavior but if not present the case cannot be labeled as benign GIST. At this point NIH guidelines are helpful in many cases, which state that size of more than 10 cm, irrespective of mitotic count, shows aggressive behavior. According to Dong et al epithelioid gastrointestinal stromal tumors may cause significant diagnostic confusion on fine-needle aspiration (FNA) with carcinomas, neuroendocrine tumors, and melanoma, particularly when metastatic. The diagnosis 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. Histopathological examination is necessary if ICC is not available. On cytology, we have given epithelioid GIST, hepatocellular carcinoma, metastatic carcinoma, neuroendocrine tumor & melanoma as differential diagnosis. Cytological features were similar those discussed by Dong et al. Differentiation between benign and malignant epithelioid GIST, on cytology is as difficult as for spindle cell GIST. Here also NIH guidelines are helpful in many cases. We found groups of histiocytes in cytology of epithelioid GISTs (possibly of exogastric mass of 14 cm diameter which is not reported in the literatures referred. Cytological findings were somewhat similar to that of hepatocellular carcinoma but absence of endothelial cells and nucleoli, along with radiological finding of the from stomach favored epithelioid GIST as first differential diagnosis. Later, the cytodiagnosis was confirmed on histology. CONCLUSION: Many authors believe that a cytologic diagnosis of GIST should not be made without ICC. 7,9 In centers where ICC facilities are not available and where the patient's future management depends on the cytologic diagnosis, a cytopathologist can suggest the diagnosis of GIST (along with differential diagnosis in case of epithelioid GIST), can give a suggestion on behavior/aggressiveness of tumor but neither confirm the diagnosis nor tell its benign or malignant character. Cytology is basically useful in classifying the tumor as epithelial vs. stromal and spindle vs. epithelioid types of GIST. [1], [2], [4] Most cytology smears show a relatively benign picture without obvious pleomorphism, Journal of Evolution of Medical and Dental Sciences/ Volume 3/ Issue 04/January 27, 2014 Page 897
anaplasia or mitoses even when these are seen on histology. 2 Since mitoses form an important criterion for the diagnosis of malignancy; assessment of malignancy should not be attempted on smears and is best left to histological examination. 1,2,6,7,8,10 Diagnosis of GIST should be considered by cytologist, both for spindle cell & epithelioid lesions of abdomen. These lesions respond very well to imatinib & do not have very poor prognosis as that of deep-seated sarcomas & hepatocellular carcinoma. REFERENCES: 1. Boggino HE, Fernandez MP, Logrono R.F. Cytomorphology of gastrointestinal stromal tumour: diagnostic role of aspiration cytology, core biopsy, and immunochemistry. Diagn Cytopathol 2000; 23:156-60. 2. Deshpande A, Munshi MM. Gastrointestinal stromal tumours report of three cases and review of literature. J Cytol 2007; 24: 96-100. 3. Fletcher CDM, Berman JJ, Corless C. Diagnosis of gastrointestinal stromal tumors: a consensus approach. Hum Pathol 2002; 33: 459-465. 4. Dong Q, McKee G, Pitman M, Geisinger K, Tambouret R. Epithelioid variant of gastrointestinal stromal tumour: diagnosis by fine-needle aspiration. Diagn Cytopathol 2003; 29: 55-60. 5. Gu M, Ghafari S, Nguyen PT, Lin F. Cytologic diagnosis of gastrointestinal stromal tumours of the stomach by endoscopic ultrasound-guided fine-needle aspiration biopsy: cytomorphologic and immunohistochemical study of 12 cases. Diagn Cytopathol 2001; 25: 343-50. 6. Li SQ, O'Leary TJ, Buchner SB, et al. Fine needle aspiration of gastrointestinal stromal tumours. Acta Cytol 2001; 45: 9-17. 7. Cheuk W, Lee KC, Chan JK. c-kit immunocytochemical staining in the cytologic diagnosis of metastatic gastrointestinal stromal tumour. A report of two cases. Acta Cytol 2000; 44: 679-85. 8. Dodd LG, Nelson RC, Mooney EE, Gottfried M. Fine-needle aspiration of gastrointestinal stromal tumours. Am J Clin Pathol 1998; 109: 439-43. 9. Kimura M, Satou T, Hashimoto S, Tabaru Y. Can GIST be diagnosed reliably by cytology? Acta Cytol 2002; 46: 1170-1. 10. Kwon MS, Koh JS, Lee SS, Chung JH, Ahn GH. Fine needle aspiration cytology (FNAC) of gastrointestinal stromal tumour: an emphasis on diagnostic role of FNAC, cell block, and immunohistochemistry. J Korean Med Sci 2002;17: 353-9. GROUP SIZE (cm) (in greatest dimension) MITOTIC COUNT (per 50 high power fields) Very low risk <2 <5 Low risk 2-5 < 5 Intermediate risk < 5 6-10 5-10 < 5 Journal of Evolution of Medical and Dental Sciences/ Volume 3/ Issue 04/January 27, 2014 Page 898
High risk >5 >5 >10 Any mitotic count Any size >10 Table-1: NIH consensus guidelines for defining risk of aggressive behavior in GISTs at any anatomical site. [3] Case no. Age/sex Clinical presentation 1. 42y/M Abdominal lump 2. 34y/M Abdominal lump 3. 50y/F 4. 61y/M Lump, pain in abdomen Lump, pain in abdomen 5. 46y/M Abdominal lump 6. 53y/F Abdominal lump 7. 49y/M Lump, pain in abdomen Radiology Cytodiagnosis Histology 7cmx6cmx4cm transmural mass, stomach 7cmx5cmx5cm transmural mass, stomach 11cmx7cmx4cm from stomach, exogastric mass. 12cmx6cmx6cm from stomach, exogastric mass. 12cmx6cmx5cm from colon, areas of necrosis seen. 14cmx11cmx7cm from stomach, exogastric mass. 16cmx12cmx7cm from colon benign) benign) (possibly (possibly Table-2: Age, sex, clinical presentation, radiological findings, cytodiagnosis & histodiagnosis of cases of 7 cases of GISTs cell, benign cell, benign cell, malignant cell, malignant Not available malignant malignant Journal of Evolution of Medical and Dental Sciences/ Volume 3/ Issue 04/January 27, 2014 Page 899
Fig. 1: Spindle cells in fascicular & whorling patterns with collagenous stroma. (MGG, x100) Fig. 2: Palisading in GIST. (MGG, x400) Fig. 3: Histology of GIST, benign. (H&E, x400) Fig. 4: Scant to moderate cytoplasm, with some vacuolization & ill-defined borders. (MGG, x400) Fig. 5: Moderately pleomorphic nuclei with high N: C ratio. (MGG, x400) Fig. 6: Epithelioid GISTs (possibly showing groups of histiocytes. (MGG, x100) Fig. 7: Epithelioid GISTs (possibly showing moderate pleomorphism. (MGG, x400) Journal of Evolution of Medical and Dental Sciences/ Volume 3/ Issue 04/January 27, 2014 Page 900
Fig. 8: Epithelioid GISTs (possibly showing loosely clustered mildly pleomorphic cells. (MGG, x100) Fig. 9: Cytoplasm with ill-defined borders & some vacuolization (MGG, x400) AUTHORS: 1. Priyanka Agrawal 2. Subhash Agrawal 3. Atul Gupta 4. Anurag Gupta PARTICULARS OF CONTRIBUTORS: 1. Assistant Professor, Department of Pathology, S.S. Medical College, Rewa, (M.P.) 2. Assistant Professor, Department of Anaesthesia, S.S. Medical College, Rewa, (M.P.) 3. Professor & Head, Department of Pathology, S.N. Medical College, Agra, (U.P.) 4. Associate Professor, Department of Pathology, S.N. Medical College, Agra, (U.P.) NAME ADDRESS EMAIL ID OF THE CORRESPONDING AUTHOR: Dr. Subhash Agrawal, F-11/1, New Doctors Colony, Arjun Nagar, Rewa (M.P.) 486001. E-mail: drsubhash24@gmail.com Date of Submission: 30/12/2013. Date of Peer Review: 31/12/2013. Date of Acceptance: 13/01/2014. Date of Publishing: 22/01/2014. Journal of Evolution of Medical and Dental Sciences/ Volume 3/ Issue 04/January 27, 2014 Page 901