Original article / research
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Role of Fine Needle Aspiration Cytology in the Assessment of Intra-Abdominal and Retroperitoneal Lesions-A Comparative Study |
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Apaparna Amogh Na ik Na mshiker, Premila De Sousa Rocha, Roque G.W. Pinto 1. Assistant Lecturer, Department of Pathology, Goa Medical College and Hospital, Goa, India. 2. Associate Professor, Department of Pathology, Goa Medical College and Hospital, Goa, India. 3. Professor and HOD, Department of Pathology, Goa Medical College and Hospital, Goa, India. |
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Correspondence
Address : Dr. Aparna Amogh Naik Namshiker, H. No. 9/15/5, Water Tank Road, Khadpabandh, Ponda, Goa-403401, India. E-mail: apkantak@gmail.com |
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ABSTRACT | |||||||||||||||||||||||||||||||||||||||||||||||||||||
: Fine needle aspiration cytology (FNAC) is a widely used valuable, accurate, and safe method which was initially applied only for readily palpable masses.But in recent years previously inaccessible lesions and deeper organs are safely aspirated using the fine needle under radiological guidance. Aim: This study was conducted to evaluate and confirm the diagnostic utility of FNAC in intra-abdominal and retroperitoneal lesions. Materials and Methods: This study was conducted on 660 patients with clinically suspected intra-abdominal and retroperitoneal lesions. Ultrasound guided (USG) or computed tomography (CT) guided FNACs were performed and the smears stained with Haematoxylin and eosin (H and E) and May Grunwald Giemsa (MGG) stains. A cyto-histopathological correlation was done where ever possible. Results: Among the 660 patients studied, 65% were CT guided FNACs and 35% were USG guided. A cytopathological diagnosis was obtained in 477 cases (72%) of which 135(28.3%) werenon malignant (benign neoplasms and non neoplastic) lesions and 342 (71.7%) were malignant lesions. Liver was the most frequently aspirated organ. Pyogenic abscess of the liver and hepatic metastasis were the commonest non malignant and malignant lesions respectively. With the available cyto-histopathological correlation, the overall accuracy was 85%, the sensitivity for true positive results was 83%, the sensitivity for true negative results was 88%, the positive predictive value (PPV) was 94% and the negative predictive value (NPV) was 68%. No major complications were observed. Conclusion: Guided FNAC was thus confirmed as a safe procedure that provides fairly accurate diagnosis with minimal complications in the diagnosis of intra-abdominal and retroperitoneal lesions. | |||||||||||||||||||||||||||||||||||||||||||||||||||||
Keywords : Computed tomography guided, Cytohistopathological, Ultrasonography guided | |||||||||||||||||||||||||||||||||||||||||||||||||||||
INTRODUCTION | |||||||||||||||||||||||||||||||||||||||||||||||||||||
As documented earlier, the correct diagnosis of abdominal lumps is difficult and often calls for a histopathological confirmation (1). This also holds true in the diagnosis of lesions in other less accessible sites like the retroperitoneum Fine Needle Aspiration Cytology is a simple, safe, inexpensive and rapid procedure which renders surgical intervention and exploratory laprotomy unnecessary. In recent years previously inaccessible and deeper organs like liver, spleen, pancreas, retroperitoneum and ovary are safely sampled and routinely aspirated using the fine needle under radiological guidance (2). Amongst the various imaging modalities, many prefer the speed of ultrasound guidance, while others are reassured by the greater resolution of computed tomography (2) . Various studies have been performed to evaluate the accuracy of FNAC in the diagnosis of intra abdominal masses (1),(3),(4),(5),(6),(7),(8). This study was conducted to further confirm the usefulness of FNAC as a diagnostic procedure in the management of intra-abdominal and retroperitoneal lesions. Our main objectives were to determine the anatomic site-wise distribution of the lesions, the age and sex distribution of patients with intraabdominal and retroperitoneal lesions, to classify and study the prevalence of non malignant (benign and non neoplastic) and malignant lesions aspirated and to correlate the cytological diagnosis with histopathology wherever possible. | |||||||||||||||||||||||||||||||||||||||||||||||||||||
MATERIAL AND METHODS | |||||||||||||||||||||||||||||||||||||||||||||||||||||
It was a retrospective study which was conducted over a period of 8 years in the Department of Pathology in a tertiary care hospital from 2000 to 2007. It included analysis of 660 patients who presented clinically and radiologically with intra-abdominal and retroperitoneal lesions. A detailed workup of patients was carried out including complete patient history, review of records and clinical examination. Majority of the patients presented with an intra-abdominal mass or organomegaly. Others included patients who presented with:– a) Symptoms of systemic involvement (e.g. dyspepsia, bleeding per rectum); b) Obstructive symptoms (e.g. obstructive jaundice) and c) Constitutional symptoms (e.g. abdominal pain, fever, weight loss etc). Intraabdominal and retroperitoneal masses detected by other radiological methods like MRI imaging were not included in this study. An Informed consent was taken and the clotting time and bleeding time were confirmed to be in the normal range. FNAC under radiological guidance (USG/CT) was performed on an in-patient basis using a22G LP needle, 10ml disposable syringe and a modified comeco syringe piston holder. Smears were prepared and stained with H&E and MGG. Repeat aspirations were done in patients where the first attempt was inadequate or was inconclusive. A cytopathological opinion was made under light microscopy by correlating with clinical and radiological findings. Histopathological correlation was carried out in patients who underwent surgical excision/ biopsy of the lesion. | |||||||||||||||||||||||||||||||||||||||||||||||||||||
RESULTS | |||||||||||||||||||||||||||||||||||||||||||||||||||||
This series of 660 patients revealed a male predominance that included 392 (59.39%) males and 268 (40.61%) females, giving a male to female ratio of 1.5:1. Cases from all age groups were analyzed and it was observed that the maximum number i.e. 153 (23.18%) cases were in the age group of 51-60 years (Table/Fig 1). The youngest that underwent the procedure was aged 19 days and the oldest was 89 years. Computed Tomography (CT) was the more common mode of radiological guidance used over ultrasonography with 427 cases (64.7%) being CT guided and 233 cases (35.3%) being USG guided FNAC. Amongst the various organs / sites aspirated, the maximum number of aspirates were of hepatic lesions (307) followed by intraabdominal lymphnodes all of which were retroperitoneal (70) (Table/Fig 2). The aspirations were categorized as diagnostic aspirates (477 cases) and non-diagnostic/inconclusive aspirates (183 cases). The nondiagnostic/inconclusive category included: a) Aspirates with inadequate material (e.g. scanty cellular material or presence of normal cellular material and b) Those with atypical cells or where the possibility of malignancy could not be ruled out (e.g. differential diagnosis of low grade HCC and regenerating nodule). Out of the 477 cases where a definite cytological interpretation was possible, cyto-diagnosis revealed 135 non-malignant lesions and 342 malignant lesions. The non malignant lesions comprised of 102 non-neoplastic and 33 benign neoplastic conditions while out of the 342 malignant lesions; 190 were primaries, 114 were metastatic and 38 were positive for malignancy. Cases positive for malignancy included those in which the smears revealed few hyperchromatic cells or clusters of poorly differentiated cells (poorly differentiated/ high grade malignancy). Hepatic metastasis was the most common malignant lesion while pyogenic abscess was the commonest non malignant lesion aspirated (Table/Fig 3),(Table/Fig 4). A cyto-histopathological correlation was available in 58 cases (Table/Fig 5). A true positive diagnosis was made in 34 cases while a false positive diagnosis was made in only 2 cases. 15 cases were true negatives while 7 were false negative. Thus the accuracy was 85% while the sensitivity for true positive results was 83% and that for true negative results was 88%. The positive and negative predictive values were 94% and 68% respectively. During the study period only minor complications were encountered with a complication rate of 0.76%. | |||||||||||||||||||||||||||||||||||||||||||||||||||||
DISCUSSION | |||||||||||||||||||||||||||||||||||||||||||||||||||||
FNB is indicated in almost every mass where the etiology is unclear. It leads to a reduction in open biopsy and two stage surgical procedures by providing a definite diagnosis prior to primary surgical treatment (2). This study further confirms its diagnostic accuracy in the assessment of intra abdominal and retroperitoneal lesions while assuring its safety as an interventional radiographic procedure. The maximum number of patients in the present study belonged to the age group of 51-60 years (23.18%).A similar age range was observed by Zawar et al., (3) and Reddy S et al., (4). A male predominance was observed with an incidence of 59%. These results tally with those of Zawar et al.,(3) Ennis and MacErlean (5), and Suman BS and Muniyappa B (9) who observed similar predominance of 65%,58%and 67.7% males respectively amongst patients who underwent FNAC of intraabdominal lesions. Amongst all the organs / sites in the present study, maximum number of aspirates were of hepatic lesions (46.52%). In the year 1980, Ennis and MacErlean (5) conducted a study where 38 patients with intra-abdominal masses underwent FNAC, 18 (47.37%) of which included patients with abnormal liver sonograms.These results also correspond to most of the Indian studies with Shanti Swaroop et al., (1), Khanna et al.,(10), Zawar et al.,(3) Reddy S et al., (4) and Suman BS and Muniyappa B (9) performing aspiration biopsies where hepatic lesions contributed to, 46.43%, 63.27%, 45%, 38% and 40% respectively of all the organs biopsied. In the present study, of the 477 diagnostic aspirates, 72.7% were malignant lesions and 28.3% were non malignant (non neoplastic and benign neoplasms). Studies conducted in the past by, Shanti Swaroop et al (1), Ennis and MacErlean (5) Zornoza et al., (6) and Goldstein et al., (7) as well as recent studies by Suman BS and Muniyappa B (9) and Al Hemalatha et al.,(11),(12) revealed the predominance of malignant lesions among the total number of intra-abdominal organs / sites biopsied by FNAC. When analysis of specific organs was carried out, the percentage incidence of common non malignant and malignant lesions in these organs was comparable to results from previous studies. Amongst the malignant hepatic lesions, metastatic lesions were the most frequent (51.88%) followed by hepatocellular carcinoma (33.8%). While this finding concurred with that reported by Khanna et al., (10), Gatphoh et al., (13), Barbhuiya et al., (14) and Fornari et al., (15), a higher incidence of primary Hepato cellular carcinoma was however observed by AL Hemlata et al., (11) and Suman BS and Muniyappa B (9). Most of the smears from hepatocellular carcinoma were moderately cellular and revealed trabercullae of malignant hepatocytes with hyperchromatic nuclei having prominent nucleoli and intranuclear inclusions (Table/Fig 6),(Table/Fig 7). The other hepatic malignancies included hepatoblastoma (1.87%) (Table/Fig 8), Lymphoma (1.25%), SPEN (0.62%) and positive for malignancy (10.63%). In the present series, of the total number of diagnostic splenic aspirates, 15.8% tested positive for malignancy and 84.2% were non-malignant lesions. Similar, findings of a higher incidence of non malignant lesions have been demonstrated by Zeppa et al., (16) and Siniluoto et al., (17). Among the diagnostic pancreatic aspirates, a higher incidence of malignant pancreatic lesions was observed in this study (90%) of which 8 cases (88.89%) were adenocarcinomas and one was case of SPEN of pancreas (Table/Fig 9). Goldstein et al., (7) conducted a study where 8 of the 14 cases having a correct or presumptive diagnosis were pancreatic carcinomas. These results were concurred upon by Jorda et al., (18). Amongst the total number of pancreatic malignancies, the increased incidence of adenocarcinomas (88.89%) noted in this study was also similar to that depicted by Jorda et al.,(18). Endoscopic ultrasound–guided fine needle aspiration cytology (EUS-FNAC) is currently the most commonly used procedure for obtaining cytologic specimens of the pancreas and studies have confirmed its diagnostic accuracy (19). Out of the malignant renal and adrenal lesions aspirated, renal cell carcinoma was the commonest (37.84%) (Table/Fig 10) followed by Wilms tumor (16.22 %), metastasis (16.22 %) and neuroblastoma (13.51%), renal squamous cell carcinoma (8.11%), positive for malignancy (5.40%) and renal oncocytoma (2.7%). Similar findings were demonstrated by Pilotti et al., (20) and Mangal N et al., (21). Renal cysts showed a higher incidence (4 of 11 cases) among the benign non neoplastic conditions, as also shown earlier by Kristensen et al., (22) in their study. Ultrasound guided aspiration of the adrenal gland revealed a benign pheochromocytoma, 5 cases of neuroblastoma, and one case each of metastasis and positive for malignancy. It is thus highly safe and specific in the diagnosis of adrenal gland lesions which concurs with the findings of Mangal N et al., (21). Lymphomas (Table/Fig 11) formed the majority of all the malignant retroperitoneal lesions followed by metastasis to lymphnodes and sarcomas (Table/Fig 12),(Table/Fig 13). While sarcomas predominated in the series carried out by Al Hemlata et al., (11), lymphomas also formed the majority in the study conducted by Khanna et al., (10). In the present study, all the conclusive aspirates from the female genital system (ovary and uterine corpus) were neoplastic in nature. Primary adenocarcinoma of ovary had the highest incidence (77.78 %) among the ovarian malignant neoplasms. These findings were concurred upon by Dey et al., (23) and Bandyopadhyay A et al., (24). Similar to the results observed by Das et al., (25) most of the GIT lesions diagnosed on cytology were malignant, commonest being gastrointestinal adenocarcinoma. In this study, cyto–histopathological correlation was available in 58 cases out of 660 cases. This may be due to fact that (1) 307 cases of the total 660 cases were aspirates from hepatic lesions. The patients diagnosed as having malignant hepatic disease are either referred to oncology institutes for specialized treatment or had convincing evidence of advanced malignancy and hence were not subjected to further histopathological diagnosis (2) Benign lesions were treated conservatively with antibiotics/ antituberculous treatment while, (3) rest of the cases were lost for follow-up. With the available cyto-histopathological correlation, overall accuracy was 85%. Sensitivity for true positive results was 83% and that for true negative results was 88%. A positive predictive value of 94% was obtained while the negative predictive value was 68%. Similar findings with a high diagnostic accuracy have been observed by Shanti Swaroop et al.,(1), Zawar et al., (3), Reddy S et al., (4), Ennis and MacErlean (5) Zornoza et al., (6) Goldstein et al., (7) Shamshad et al., (8) and Khanna et al. (10) Limitations While only minimal complications occured, the high percentage (28%) of non diagnostic lesions was a drawback of this study. This can however be attributed to the fact that: 1) The cases with in adequate material (i.e. scanty aspirate, only blood aspirated, necrotic material only and normal epithelial cells); those with atypical cells as well as those where the benign or malignant nature of the lesion could not be ascertained were included under the category of nondiagnostic / inconclusive cases. 2) Lack of ancillary diagnostic techniques (immunocyto chemistry and cell block method). 3) Non – compliance of patients during repeat aspirations contributing to the number of cases with inadequate material. | |||||||||||||||||||||||||||||||||||||||||||||||||||||
CONCLUSION | |||||||||||||||||||||||||||||||||||||||||||||||||||||
The study conducted showed a high accuracy and a high sensitivity of FNAC in diagnosing intra–abdominal and retroperitoneal lesions under radiological guidance with minimal complications. However, efforts are being made to reduce the number of false positive aspirates by considering the various criteria described in literature to differentiate between malignancies and benign conditions mimicking the same. An attempt has to be made to decrease the percentage of nondiagnostic /inconclusive lesions by improving the modalities of radiological guidance using fine needles with radio opaque tips, performing further analysis of aspirates using ancillary techniques like immunocytochemistry and cell block methods and lastly and by honing the technical and diagnostic skills of cytopathologists. | |||||||||||||||||||||||||||||||||||||||||||||||||||||
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TABLES AND FIGURES | |||||||||||||||||||||||||||||||||||||||||||||||||||||