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CT Guided Transthoracic FNAC of Intrathoracic Lesions-An Institute Experience |
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Nishaa prathap, Pattabhiraman, Raghuram, Siddharth Biswas 1. Assistant Professor, Department of Radiodiagnosis, ESIC Medical College and PGIMSR, Bengaluru, Karnataka, India. 2. Professor, Department of Radiodiagnosis, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India. 3. Professor, Department of Radiodiagnosis, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India. 4. Professor, Department of Pathology, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India. |
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Correspondence Address : Dr. Nishaa Prathap, Shreyas, No.9, 1 Cross, Sir MV Nagar, Kalkere Road, Ramamurthy Nagar, Bengaluru-560016, Karnataka, India. E-mail: dr.nishaa.narayan@gmail.com |
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| ABSTRACT |  | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
: Introduction: In the management of thoracic lesions, especially malignant lesions, specific pathological diagnosis is considered standard, so obtaining the tissue is essential for diagnosis and treatment. There are complex vascular structures in hila and mediastinum and so precise localization is necessary to avoid unnecessary injury to these structures, which can be achieved by doing image guided procedures. Aim: This study was proposed to analyze the role of CT in guiding the FNAC of the thorax and to understand its scope in improving the diagnostic accuracy and therapeutic outcome, decreasing the patient discomfort, cost and surgical morbidity and also in assessing the types of complications arising out of the same. Materials and Methods: This prospective observational study was conducted at Kidwai Memorial Institute of Oncology Bengaluru, India, from 2012 to 2015 for three years. This study consisted of 420 patients who were referred for TTFNAC. Results: The Study consisted of 420 patients in age group of 18-87 years. Total yield of 85% was achieved, complications were seen in 84 patients (20%)in the form of pneumothorax and hemorrhage. Maximal lesions encountered were seen in the lungs, followed by mediastinum. The sensitivity specificity, positive and negative predictive values are 97%, 66%, 94% and 82% for malignant lesions. However, it was lower for benign lesions. Conclusion: CT-guided Transthoracic (TTFNAC) is a good tool for material procurement in benign and malignant lesions. It helps the clinician to initiate appropriate treatment measures like chemotherapy or radiotherapy at an early pace and is associated with low mortality and morbidity. TTFNAC achieves substantial cost savings, as it can obviate more costly and invasive surgical procedures and is minimally invasive. Fewer complications are caused by TTFNAC that can be avoided, if properly planned by avoiding vessels and bullae. However, if they occur they can be easily managed. This procedure can be used as a safe outpatient procedure for material procurement in lung or mediastinal lesions, not accessible for ultrasound guided FNAC, for lesions situated less than 8 cm from chest wall and size greater than 25 mm and it has good patient tolerance. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Keywords : Lung FNAC, FNAC of mediastinal lesions | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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DOI and Others :
DOI: 10.7860/IJARS/2017/31142:2418
Date of Publishing: Jul 01, 2018 FINANCIAL OR OTHER COMPETING INTERESTS:None. |
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| INTRODUCTION |
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Intrathoracic mass is a common problem encountered by the clinicians worldwide but it is difficult to diagnose correctly (1). In oncology, pathological diagnosis is of paramount importance and is always standard for diagnosis, treatment and staging of the disease (2). FNAC is a method of taking cytology sample by means of a fine needle attached to a syringe (1). In 1983, for detection of infections and malignancies, the technique of diagnostic lung puncture was first introduced by Leyden and Menbriel in 1986.This method was first used by Menetrier in diagnosing lung carcinomas (3). A Computed Tomography (CT)-guided TT FNAC is a technique where lung, mediastinal or pleural tissue cells are obtained using a CT-scan to guide FNAC (4). Keywords: Lung FNAC, FNAC of mediastinal lesions Presence of complex vascular structures in the mediastinal and hilar areas demand the precise localisation and route for needle aspiration cytology. Haaga and Alfidi reported the first CT-guided biopsy in 1976 (3),(4). Availability of an onsite cytopathologist or a cytopathology technician can confirm the adequacy of the harvested specimen; hence it decreases false negative results or inconclusive results (5). CT guided FNAC helps in good anatomical display, easier diagnosis, improved staging, increased chance of effective intervention and to formulate early and effective management of the lesion with avoidance of thoracotomy (6). Complications from image guided needle cytology are infrequent and generally minor, particularly when 22-gauge needles are used. Pneumothorax is the principal complication of CT-guided chest FNAC, may be decreased by minimizing the amount of aerated lung traversed (7),(8). It almost always is self-limited. Whenever possible, vessels, bronchi, and bullae should be avoided to minimize hemoptysis. The needle-track seeding is a rare occurrence with incidence of about 0.01% (7). | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Material and Methods |
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This prospective hospital based observational study was conducted at the Department of Radiodiagnosis of Kidwai Memorial Institute of Oncology, between the period of November 2012 to March 2015. This study consisted of 420 patients who were referred for TTFNAC. Informed consent was obtained from all the patients or their relative after explaining them the procedure proposed and the possible complications that may arise from the same, in a language understood by them. Sample size was calculated as 420 and the power of the study was 80% as calculated by the statistician based on prevalence of disease and number of cases referred. Success of each procedure was established at final report. Material adequacy was calculated. CT diagnosis was compared with histopathology in benign and malignant lesions. Heterogenous enhancement of the lesion, presence of necrosis, size greater than 3 cm, surface lobulation, irregular border, spiculation, corona radiata, pleural effusion, chest wall invasion, vascular invasion, calcification, collapse, lymph nodes and necrotic areas within, thick walled cavity (with wall thickness more than 4 mm) were considered sign of malignancy. If equivocal findings were present, it was considered benign lesion. Inclusion criteria: 1. Undiagnosed mediastinal, hilar, pleural or pulmonary mass lesion on CT-scan. 2. Thoracic lesions with normal bronchoscopic findings. 3. Indeterminate lesions or masses to confirm the nature of the lesion. 4. Lesions greater than 20 mm, not abutting vascular structures, lesion present at less than 8 cm depth from chest wall. 5. Single or multiple nodules when metastases are suspected. Exclusion criteria: Patient with abnormal coagulation profile (prolonged PT/APTT), severe thrombocytopenia (platelet count <50,000), bullous emphysema, pulmonary hypertension, lesion less than 20 mm, abutting vascular structure or hila, lesion situated at a depth more than 9 cms from chest wall were not considered for the study. Also, the pediatric patients, non co-operative, unconscious patient or severely ill patient, patients with abnormal bleeding parameters and history of bleeding diathesis were not included. Patients with intractable cough were excluded from the study. Procedure: Patient was positioned in the CT gantry based on closer proximity to the lesion either in supine, prone or decubitus based on review films (Table/Fig 1). Non-contrast CT was obtained from the neck base to the diaphragm domes to delineate the lesions and locate the needle puncture site. This also helped to determine the optimal patient position, needle entry site, and pathway to the lesion with an attempt to avoid major nerves or muscles. Shortest distance to the lesion was identified so as to traverse the least amount of lung parenchyma and to avoid blood vessels or bullae. Major and the minor fissure were not traversed to avoid seeding or upstaging of the tumour. The appropriate level for FNAC was found and the needle entry site was selected. The distance to the lesion and the angle of entry was planned on the CT monitor at the console. Using the CT-LASER localizing light, which delineated the selected transaxial level on the surface of the patient, a radiopaque marker (needle) was placed on the skin at the entry site (Table/Fig 2). Ideally, the shortest straight line from skin to the lesion should be chosen, although a longer needle path was selected sometimes to avoid critical structures (Table/Fig 2). A repeat CT-scan is performed to confirm that the marker location is appropriate for needle entry. Skin entry site is marked with marker pen by using LASER light from the CT gantry and the radiopaque marker is removed (Table/Fig 3). Percutaneous access site was prepared. Area was disinfected with Povidone Iodine and surgical spirit and draped. 18-22 gauge spinal needle was used and inserted directing the needle tip towards the lesion. FNAC needle was inserted into the subcutaneous tissue. The incremental adjustments in the needle angulation were made and their adequacy was assessed. The needle was advanced to the pre-measured depth. A gritty sensation or increased resistance was felt when a solid lesion was entered (Table/Fig 4). After needle advancement, when the tip of the needle was located in the outer edge of the lesion, repeat slice of the area was taken to check the position of tip (Table/Fig 5). The key to recognition of the needle tip on CT was identification of an abrupt, squared end, associated with a black shadowing artifact in the adjacent soft tissues. If the needle tip was not within the lesion, it was redirected by manipulating the needle hub by changing the angle, length or both. Once the needle tip was documented to be in the lesion, material was sampled by removing the stylet of the spinal needle and a syringe was attached to the spinal needle. A 20 cc syringe was used and continuous negative pressure was applied with to and fro motion of the needle until the needle hub has an aspirate (Table/Fig 6). The needle with the syringe was handed over to the onsite cytopathology technician to make smears which were immediately fixed. A maximum of seven smears is made, if indicated, a specimen was also sent for microbiological evaluation (Table/Fig 7). Success of each procedure was established at final cytology report and final diagnosis was made. Immediate post procedure, compression was given at the site of intervention to stop bleeding and a dressing is applied. A repeat CT was done in the area of interest, to rule out pneumothorax (Table/Fig 8). In case of pneumothorax, patient was observed for four hours. Ethics: This study was approved by scientific and ethical committee at Kidwai Memorial Institute of Oncology, Bengaluru, India. Statistical analysis Descriptive analysis was adopted to study data using percentages. Efficacy of CT guided FNAC was computed using yield and failure rates. Validation of CT guided TTFNAC in diagnosing benign and malignant lesions were computed by calculating sensitivity, specificity, positive and negative predictive value. Complications were divided in terms of pneumothorax, hemoptysis, death or hemorrhage and percentages were calculated. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Results |
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Image guided thoracic interventions are routinely performed of which those done under CT guidance are widely used now a days. For the current study, 420 patients underwent CT guided TT FNAC. In the present study, patients were in the age group of 18-87 years of age; the most common age group encountered was 50 to 60 years followed by patients in the age group below 50 years. Youngest patient encountered was 18 year and oldest was 87 year. This study included 285 males (67.8%) and 135 females (32.1%). In the current study, the most common site of the thoracic lesions seen was intrapulmonary 360 (85.7%), followed by mediastinal masses 51 (12.1%) and remaining were pleural lesions 9 (2.1%) (Table/Fig 9). The lesions varied in size from 15 mm to 106 mm, however the lesions less than 25 mm yielded no material. In intrapulmonary lesions, the most common sub-site involved was left upper lobe followed by right lower lobe. Other lesions were mediastinal and pleural, in the mediastinum the most common sub-site was anterior mediastinum. All the 420 patients underwent CT guided TTFNAC procedure, material was procured in 402 patients, i.e., on CT table cellular material could be aspirated from 402 patients and these were handed over to a cytopathologist, present at the procedure room to prepare the smears. In the rest of the 18 cases no material could be aspirated on repeated efforts. Material procured by CT guided TTFNAC was handed over to cytopathologist who prepared an average of 5 smears for each case, these slides were fixed and stained adequately by using Papanicolaou, Giemsa or Hematoxylin and Eosin in case of cell block specimens. In a fewer cases cell block study was attempted to further characterise the lesion, in case of suspected infective etiology the aspirate was subjected to microbiological examination. When the samples had a high cellularity, they were defined as adequate. This constituted to about 85% cases. Samples were considered inadequate when cellularity was poor or absent and when there was necrosis or bloodstained material as no definitive diagnosis could be given in these cases. These cases were considered as procedure failure and these patients were subjected to repeat examinations. However, in the lesion smaller than 25 mm, the yield was very poor. A total of 66 benign lesions and 267 malignant lesions were diagnosed based on final cytological diagnosis. In the intrapulmonary lesions, 66 lung lesions were considered benign, out of which 30 patients showed granulomatous cells, 24 patients showed inflammatory cells, nine cases had hydatid cyst (Table/Fig 10) and three patients had abscess. In the patients with granulomatous cells, microbiological evaluation of the aspirated material was done (Table/Fig 11) (a-d). In the malignant intrapulmonary lesions, the most common were primary (75%) followed by secondary (25%). Amongst the malignant lesions, the most common subtype encountered was non small cell type (61.2%), followed by small cell type (23.5%), poorly differentiated carcinomas (10.11%) and 3 round cell morphology cells (3%) cases, which was confirmed as lymphoma on cell block. Amongst the non small cell carcinomas, adenocarcinoma was more common subtype, followed by squamous type (Table/Fig 12). The radio cytological concordance for the malignant lesions was good, as sensitivity, specificity; positive and negative predictive values for malignant lesions were 97.2%, 66.66%, 94.5% and 82.0% respectively. The radio cytological concordance for the benign lesions was lower, fewer lesions attributed as benign on CT were confirmed, and sensitivity, specificity, positive and negative predictive values for benign lesions were 66.6%, 97.2%, 80% and 94.7%. The sensitivity of the CT for the benign lesions is lower than malignant lesions however specificity is higher and hence it is suggested to follow-up the patients for a period of at least three months before subjecting the patient to interventional procedures in particular in smaller nodules less than 25 mm. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Discussion |
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Amongst the mediastinal masses, lymphoma was the most common subtype which showed round cell morphology and was confirmed by immunohistochemistry. Thymoma was seen in 2% cases (Table/Fig 13) (a-d). Followed by neurogenic neoplasm, (Table/Fig 14) (a-d) lymph nodal metastasis was seen in six cases, three case of mature teratoma was seen. The mediastinal lesions showed good radiological and cytological agreement in cases of teratoma, thymoma, lymphoma and neurogenic neoplasm and less in neuroendocrine tumour metastasis. In the present study, patients were in the age group of 18- 87 years, the most common age group encountered was 50 to 60 years followed by patients in the age group below 50 years. Youngest patient encountered was 18 years and oldest was 87 years. Mean age was 52.5 years. Pediatric patients were excluded from the study. In this study most common lung lesions were encountered in left upper lobe followed by right lower lobe. Least number of lesions was seen in right middle and right upper lobes (Table/Fig 15). Based on assessment of CT features of the available review CT-scans, these lesions were classified as benign, malignant or indeterminate, about 217 CT-scan showed malignancy features, 36 CT scans showed benign features and 96 cases were indeterminate. Most of the malignant lesion show heterogenous enhancement, necrotic areas and spiculated or thick walled borders (Table/Fig 16). The rate of post procedure complications was studied in all the cases, by doing an immediate check plain CT. A total of 126 patients developed minor complications, no death was encountered, and no patients needed chest tube insertion. Pneumothorax developed in 20% cases (Table/Fig 12). All of these lesions were at a depth exceeding 4.5 cm from the chest wall. 39 cases were at an angle of more than 90 degrees from the chest wall, three cases had cavitary lesions (Table/Fig 17). In the present study about 42 patients developed intrapulmonary hemorrhage, these lesions were at a depth of more than 2.5 cm from the chest wall. Lesion depth has been identified as the most important risk factor. Haemorrhage may occur from intercostal or internal mammary arteries or veins. In the malignant intrapulmonary lesions, the most common lesions were primary which constituted to about 75% and 25% secondary lesions were seen. Most common lesions encountered in this study were primary lesions. Comparison with other studies is tabulated in (Table/Fig 18). this study showed similar diagnostic accuracy and complication rates compared to other studies (5),(7),(8),(10),(7),(11). In a study conducted by Adyakinkar et al., total cases were 60, out of which 40 pulmonary lesions were encountered, the diagnostic yield was 88%, with p-value of 0.01, sensitivity was 90% and specificity of 85.7% (12). In a study conducted by Gosh S et al., Out of 86 cases, 82 cases were pulmonary lesions of which most common encountered lesion was squamous cell carcinoma, there were minimal complications in the form of pain (14). In a study conducted by Baby J et al., of the 114 cases there were 96 lung lesions, diagnostic yield was seen in 100 cases with diagnostic accuracy of 87.7% and 3% cases developed pneumothorax (14). In a study conducted by M Sengupta M et al., 74 cases of pulmonary lesions were studied. All malignant lesions showed good yield. Minimal complications were encountered (15) In a study conducted by Bharadwaj P et al., FNAC showed diagnostic yield of 95.9% and complications in 8.2% (16). In a study done by Sharma et al CT guided FNAC was done in 81 patients, it yielded positive results in 75 patients (17). The clinical significance of this study is that CT guided TTFNAC can be used for material procurement in lung, mediastinal and pleural lesions that is not accessible by ultrasound. Complications can also be avoided to a fair extent and if any can be diagnosed early. Recommendations TTFNAC can be used as an outpatient procedure for procurement of material in intrathoracic lesions as the yield of the procedure is good with lesser complications. Whenever possible it is suggested to aspirate at least 5-6 ml of aspirate, so that cell block (IHC markers) can be assessed in the same setting as this helps in providing more accurate pathological diagnosis. It is better to do a plain and contrast CT-scan and correlate it with CT guided TTFNAC as there will be precise lesion localization, improved staging, better identification and characterization of the masses, determine their relationship to major vessels, thereby avoiding inadvertent puncture of vascular structures and vital organs. It is better for a cytopathologist or technician to be present when CT guided TTFNAC is done so that material procurement can be assessed on the spot. If the depth of the lesion is greater than 5 cm from the chest wall, it is better to anticipate pneumothorax or complications, by observing the patient for at least 24 hours. Limitation Being oncology setup, number of malignant lesions was encountered more than benign lesions. Pediatric population was excluded from study and hence efficacy in pediatric patients could not be assessed. As USG, FNAC was done for peripherally accessible lesions in our setup, no cases of mesothelioma, other mediastinal masses, other pleural based and peripheral lung lesions were seen, hence the spectrum of lesions encountered in this study do not represent the true spectrum of intrathoracic lesions. For lesions lesser than 25 mm in size, no cellular material was aspirated even on repeat efforts. For the heterogeneous lesions, and necrotic lesions, as no contrast was used during the procedure, it was difficult to localize the most cellular aspect of the lesion, thereby necessitating multiple aspiration attempts. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Acknowledgement |
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Authors will like to thank Dr. Malathi, Department of Pathology for pathological interpretation, Dr. Ramesh for statistical analysis and Radiology Technicians of Kidwai memorial institute of oncology, Dr. Navin Patil, Dr. Deshpande Pooja Rajeev, Dr. Elroy Furtado, Dr. Anuradha Kapali, Dr. Chinchu, Pream, Dr. Prashanth Sinha, Dr. Sateesh Kumar Atmakuri, Dr. Bangar Ravindra Shivaji, Dr. Nandan Kumar, Dr. Jaipal and Dr. Madhu for the immense help in this study without which this study would be incomplete. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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