Keywords
Computed tomography - cytopathologist - fine-needle aspiration biopsy - lung cancer
Introduction
The lung together with the bronchi account for highest incidence rate of invasive
cancer in males and females, as per WHO estimates. Accurate cytological diagnosis
of pulmonary lesion is vital for detecting lung cancer. Percutaneous computed tomography
(CT)-guided lung biopsy has a high reported accuracy for obtaining a cytological diagnosis.[1],[2] Many investigators have observed that the diagnosis of CT-guided biopsy of chest
lesion depends on numerous variables such as location of lesion, lung capacity (forced
expiratory volume in one second/forced vital capacity), depth of lesion, size of lesion,
needle size, technique and type of biopsy device, number of passes, and presence of
an onsite cytopathologist. The most common complication of percutaneous lung biopsy
is pneumothorax, which has been reported to occur between 9% and 44% of the patients.[3],[4],[5],[6],[7]
Reported risk factors for pneumothorax are lesion depth, angle of needle path, and
the number of needle passes. A short depth and a needle path that is near perpendicular
to the pleura have been associated with reduced incidence of pneumothorax.[8] Other reported complications are hemoptysis, intrapulmonary hemorrhage with an increased
risk of bleeding in lesions of depth more than 2 cm,[9] pulmonary venous air embolism leading to air within the intracerebral or coronary
circulation, hemothorax and rarely implantation of malignant cells along the needle
tract.[10]
Fine-needle aspiration biopsy (FNAB) has an accuracy of up to 95% for malignant lesions
[11] but the yield for benign lesions is only (10%–50%).[12],[13],[14] Cytology is reported to be less reliable than histology in determining the cell
type in malignant lesions. There is wide variation in reported diagnostic accuracies
of FNAB between different institutions, ranging from 64% to 97%.[15],[16] A high diagnostic accuracy is best achieved with large nodules.[15],[16],[17],[18]
Materials and Methods
The study was carried out in the Department of Radiodiagnosis and Interventional radiology,
from July 2011 to December 2013. Seventy patients were included in the study. The
Ethics Committee of the institution approved this prospective cross-sectional study.
Informed consent was taken from all the patients undergoing study. Based on the results
available from existing literature on the percentage of positivity, in the presence
and absence of an onsite cytopathologist [19] and with 95% confidence and 80% power minimum sample size comes to 35 in each group.
Our inclusion criteria included patient population of any age or sex with a suspicious
lung lesion for a cytological confirmation through CT-guided chest FNAB of; (1) A
solitary nodule, or a nodule which is not amenable to biopsy by bronchoscopy; (2)
Multiple nodules suspicious of malignancy; (3) Persistent infiltrates (single/multiple)
but no diagnosis on sputum culture, serology, bronchoalveolar lavage; (4) Hilar mass
and a negative bronchoscopy. We excluded partially treated patients or those post-radiation
or post-chemotherapy patients requiring FNAB.
Pre-procedure investigations including complete blood count, prothrombin time international
normalized ratio, virology, etc. were done. Plain and contrast enhanced CT chest was
done if not availed before the procedure. FNAB was done on an OP basis after obtaining
informed consent. On the table, a multi detector CT scanners 64 or 16 slice (Siemens)
patient was positioned on the CT table in a prone, supine, or decubitus position as
appropriate [Figure 1]. A CT scan of the thorax was performed. If an adequate CT is available, then a limited
CT of thorax was taken. A needle path that shall avoid ribs and vascular structures
was selected. Each needle path was chosen so as to have the shortest possible depth
and the most perpendicular angle to the pleura. The skin entry site was marked using
a laser grid system. The entry site cleaned and prepped in the usual sterile fashion.
Local anesthesia administered using 2% lidocaine. A 20F or 22 FNAB needle advanced
under CT guidance to the edge of the lesion. Breath holding technique was employed
while crossing the pleura. The sample was then sent to the cytologist for evaluation.
An onsite pathologist was present in a group of patients. Repeat passes performed
as needed.
Figure 1: A 59‑year‑old female, mediastinal lesion under evaluation. Patient placed
in prone position, posterior approach
A positive cytology result is considered for any cytology that is definitively diagnostic
(e.g., squamous carcinoma or adenocarcinoma) or a report that is suggestive or suspicious
of a diagnosis (e.g., highly suspicious, atypical, and not able to exclude carcinoma).
A negative cytology is one which turned out to be paucicellular or inadequate sample.
Post procedure chest radiograph was performed in all patients 1 hour after the FNAB.
Small pneumothoraces was managed conservatively with monitoring of vital signs and
follow up chest X rays.
Pneumothoraces that is causing respiratory distress was planned to be managed by placement
of a pleural catheter and admission to an inpatient service. Diagnosis was confirmed
with a post-surgery histopathology report or a repeat core needle biopsy after FNAB
or the FNAB report itself.
Discussion
With an increasing need for histopathological characterization of lung pathology,
and with advent of evolving technologies such as needle technology, multiplanar imaging,
and immunohistochemistry. CT-guided FNAB has evolved to be an accurate and safe method
for obtaining tissue sample for histopathological characterization of pulmonary or
mediastinal lesion. The main objective of guided FNAB is to rule out an underlying
malignancy although it can be used for definitive diagnosis of some benign neoplasms
and infections such as tuberculosis.[20]
The reported accuracy of FNAB in the literature ranged from 64% to 97%.[21] In this study, the diagnostic accuracy of CT-guided lung FNAB was 80%.
Immediate assessment for cytological yield by an onsite cytopathologist with further
passes made when necessary had been shown by previous studies to improve the adequacy
of cytological yield.[22],[23],[24] In this study, the cytological yield and adequacy rose significantly in the group
of patients in the presence of an onsite cytopathologist. There was no significant
correlation in the presence of cytopathologist affecting other factors such as number
of passes or complications.
The incidence of pneumothorax due to FNAB is variable in the literature in the range
of 5–45%.[6],[25] In the present study, the incidence of pneumothorax was 22.8% [Figure 2]. While the location of the lesion, needle size, number of pleural passes and presence
of cytopathologist did not show any statistical correlation with the pneumothorax
rate; we noticed that the incidence of pneumothorax was significantly higher in patients
where an intervening parenchyma was traversed during biopsy. Similar observations
were made by Haramati and Austin [26] and Cox et al.[27] The pneumothorax during our study was mild-to-moderate requiring no chest tube drainage
or hospitalization.
Figure 2: A 69-year-old smoker, patient placed in lateral decubitus. Mild Pneumothorax
seen at non dependant portion. Cytology was adenocarcinoma
Pulmonary hemorrhage may occur with or without hemoptysis [Figure 3]. The incidence is variable in literature, intrapulmonary hemorrhage is recorded
in the range of 5%–16.9% and hemoptysis in 1.25%–5%.[28],[29] In the present study, the incidence of pulmonary hemorrhage was 22.8%, which was
minor and asymptomatic without any hemoptysis, hypoxia, or shock.
Figure 3: A 40-year-old male with Mediastinal lesion under evaluation. Pulmonary hemorrhage
visible in the previous needle track site. Cytology was benign teratoma
The study had few limitations,
-
Few authors have emphasized that the angle of the needle path with respect to pleura
is a novel predictor of pneumothorax. However, we did not look into this particular
parameter in the present study
-
Radiologically, suspicious lesions with adequate cellularity were reported to be benign
in the cytopathology report, and we did not repeat the FNAB procedure when there was
a strong suspicion of malignancy.
CT-guided lung FNAB is a common procedure done in most radiology departments. While
the procedure is simple, complications are not rare and reports of “inadequate sample”
are very common and frustrating. Close attention to details of technique and collaborating
“live” with a cytopathologist will go a long way in making the procedure safe and
provide a high yield.
Conclusion
-
CT-guided transthoracic FNAB is an accurate method to rule out malignancy with reasonable
rate of complication
-
Presence of an on-site cytopathologist significantly improves the adequacy of yield
for a conclusive cytodiagnosis and should be routinely employed
-
Pneumothorax and pulmonary hemorrhage are the most common complications as a result
of FNAB
-
The incidence of pneumothorax is higher when there is intervening lung parenchyma.
