ROLE AND ACCURACY OF COMPUTED TOMOGRAPHY GUIDED FNAC OF THORACIC LESION

Kshama Tiwari 1 and Kshitij Tewari 2 , 1. Assistant Professor, Era’s Lucknow Medical College and Hospital. 2. General Physician, Vivekanand Hospital, Varanasi. ...................................................................................................................... Manuscript Info ABSTRACT ......................... ........................................................................ Manuscript History


Material And Methods:-
This study is a hospital based prospective study & carried over a period of one year (September 2011 to October 2012). Investigations prior to aspiration:- Relevant investigations including BT, PT and INR etc. has to be done.  Plain & contrast C.T. of chest is to be done prior to C.T. guided aspiration.
C.T. guided FNAC is carried out as an outpatient procedure after explaining the risks and benefits and obtaining informed consent in every case. First, an axial scan of area of interest is done to locate the lesion; the best approach (supine or prone) is judged and the skin puncture site is marked with a radio opaque marker. After cleaning and draping, local anesthetic agent (2% xylocaine) is infiltrated at the site of puncture. The 22-gauge spinal needle is then inserted during suspended respiration, directing the tip of needle towards the lesion. With the tip of the needle located in the outer edge of the lesion, a repeat slice of the area of interest is taken to check the exact position of its tip. The stylet is then withdrawn 2-3 cm and the needle is advanced into the mass with a rotating motion during suspended respiration, so that its tip lies within the target lesion. 20-ml syringe is attached to the needle's hub and the plunger is pulled back, and during continued hard suction, the needle is jiggled to free material from the lesion to the needle's lumen. The aspirate is smeared on slides and fixed in 95% alcohol for hematoxylin & eosin staining or papanicolaou staining for cytological evaluation. A repeat slice in the area of interest is taken to rule out pneumothorax. If any amount of pneumothorax developed, patient is kept under observation for 24 hours and a chest x-ray PA view is done after 24 hours to rule out any subsequent development of pneumothorax. In case no complication arose, patient is discharged. This study was based on examination of 55 patients. Table 1 shows distribution of studied cases according to their age and sex. Among all studied 55 cases, 41 were male and the remaining 14 were female. The ratio of male to female was 2.93:1. A gender wise profiling of the patients' age revealed that the mean age was 51.22(±16.40) years for the male and 48.00(±15.55) years for the female. The age group of the patients in the study ranged from 16 to 80 years. Maximum number of patients (40) was in the age group of 40-69 years, accounting for 72.73% of total sample; highest share (29.10%) in age group of 60-69 years. The trend was observed both for male and female. 5 of the patients were 70+, all male. 3 of the patients were in the age group of 11-20 years.  Table 2 shows site wise distribution of all cytologically proven 52 lesions between non -neoplastic and neoplastic as rest 3 cases remain cytologically in-conclusive because of insufficient material. Out of 52 lesions, 41 (78.85%) were neoplastic and 11 (21.15%) non-neoplastic. In non neoplastic lesions; 5 were from lung, 2 each from mediastinum & thoracic vertebrae and one each from hilar and paraspinal soft tissue regions. And in 41 neoplastic lesions majority (n=30, 73%) were from lung, 6 from mediastinum, 2 from pleura and one each from hilar, thoracic vertebrae & paraspinal soft tissue regions. Thus, it was seen that neoplastic lung lesions were the dominant of all thoracic lesions. The non-neoplastic lesions, studied were of types acute inflammatory lesion (organized abscess), chronic non-specific inflammatory lesion, tubercular granulomatous lesion and haematoma.

Table 3:-Distribution Of Various Neoplastic Lesions
The site wise distribution of specific neoplastic lesions as diagnosed during our study is tabulated above in table 03. Malignant lesions, were predominant, accounting for 97.56% in which bronchogenic malignancies were the most common. In bronchogenic malignancies, 'squamous cell carcinoma' was the most common type accounting for 13(44.82%) cases out of total 29 followed by 'adenocarcinoma' with nine cases (31.03%), and 'bronchioloalveolar carcinoma', accounting for three cases(10.34%). Two cases were of 'large cell type' (6.67%), one each of 'small cell carcinoma' (3.45%) and 'poorly differentiated carcinoma' (3.45%). There was one case (3.3%) of metastatic deposits from a known patient of breast carcinoma.
Among six mediastinal lesions, two were diagnosed for squamous cell carcinoma, one each for adenocarcinoma & bronchioloalveolar carcinoma and two cases were diagnosed as non hodgkin lymphoma.Two cases pertained to pleural lesions, one was benign fibrous mesothelioma and the other malignant mesothelioma. In paraspinal region, metastatic deposits was found from a known case of carcinoma stomach (adenocarcinoma). The neoplastic lesion from hilar region was diagnosed to be lymphoma and from thoracic vertebral region, metastatic deposits from bronchogenicmalignancy (adenocarcinoma). . This male predominance has been attributed to higher incidence of tobacco smoking behaviour among males. The peak age of incidence (60-69 years) in the study was observed to be same as that of the peak age of incidence in two other studies done by Jayashankar et al 9 (60-69 years) and Basnet et al 13 (60-69 years). However, this peak age of incidence was a decade more than that documented in a study by Saha A et al 7 , in which peak age of incidence was in the range of 51-60 years. Most of the patients in this study were in the range of 40 -70 years which was similar to the study done by Mukherjee S et al 10 (40-70 years). The mean age of presentation was 51(±16.4) years which was almost same as that of 52(±15) years which was mean age of presentation of a study conducted by Kalhan S et al 14 16 where 65.2% lesions were neoplastic and 32% were non-neoplastic. Out of 11 non neoplastic lesions; 5 were from lung, 2 each from mediastinum & thoracic vertebrae and one each from hilar and paraspinal regions. Among pulmonary parenchymal lesions; acute suppurative inflammatory lesions were the most common followed by chronic non specific inflammatory lesions. In both mediastinum and thoracic vertebra, one lesion each of abscess and chronic non specific inflammation was found. In hilar region there was a single case of tubercular granulomatous lesion and one lesion of haematoma was found in paraspinal region.
Among neoplastic lesions, the malignant lesions were predominant accounting for 97.56% which was similar to the studies by Rangaswamy et al 16 11 and Kalhan S et al 14 prevalence of adenocarcinoma was found to be more than that of squamous cell carcinoma. In the present study bronchioloalveolar carcinoma (10.3%) was the third most prevalent carcinoma type, followed by large cell type (6.85%). The prevalence of small cell carcinoma and poorly differentiated carcinoma was equal and of 3.44% each. This pattern of prevalence was similar to the study done by Rangaswamy et al 16 and Sing JP et al. 12 There were three cases of metastatic malignancy, one in lung which was from known case of carcinoma breast , other in paraspinal region, from known case of carcinoma stomach and third was in thoracic vertebrae from a known case of bronchogenic malignancy . One case each of benign and malignant mesothelioma was also seen in the study. Incidence of pleural lesions was found low in our study, which was comparable to other studies like Rangaswamy et al 16 10 .
Lower specificity at 76% was recorded by Jayashankar et al 9 and at 84% by Basnet et al. 13 Positive predictive value of our study was 100% which was similar to that of found in studies by Singh JP et al 12 and Sarkar RN et al 8 and negative predictive value was found to be 80% which was almost comparable to that found in studies done by Singh JP et al 12 (75%) and Basnet et al 13 (81%). Thus the validity parameters of our study showed that the cytological diagnosis was better than diagnosis made by only radiographic findings. Thus Computed tomography guided fine needle aspiration cytology is the one of the best way of providing a diagnosis in inoperable patients and perhaps the greatest value to the clinician.

Conclusion:-
Diagnostic accuracy of C.T. guided trans thoracic fine needle aspiration cytology is quite high in determining the malignant etiology of a thoracic lesion so it should preferably be performed early in the diagnosis of thoracic lesions, especially in bronchogenic malignancies where early diagnosis and resection remain the best chances of patient survival. Thus, we conclude that C.T. guided trans thoracic fine needle aspiration cytology using a 22 gauge spinal needle is a highly sensitive and specific technique with a good diagnostic accuracy and can be used safely as an outpatient procedure in the diagnosis of thoracic lesions.