What is the Smallest Lung Nodule that can be Biopsied?
With the advent of multi-detector CT scanners and volume scans, more and more lung nodules are being picked up. Most nodules < 5 mm in diameter can be left along and will turn out to be benign. However nodules > 8 mm in diameter should be biopsied as far as possible, unless there are definite criteria to call them benign or metastatic.
With experience and the use of CT fluoroscopy it should be possible to biopsy nodules as small as 7.5 mm in diameter (Figs. 1-3). The patient has to be co-operative with his/her breathing and the nodule should be well visualized. If these two conditions are met, then it should be possible to spear the nodule with the biopsy gun cannula and to then take multiple core pieces out.
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| Fig.1 |
Figure 1 (A,B): Metastatic breast cancer. This lady with breast cancer, treated two years ago, presented with a small 8.5 mm nodule in the lung. A biopsy was successfully performed (arrow in B) and it turned out to be metastasis. It was also possible to do immunohistochemistry and ER/PR studies on the samples obtained.
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| Fig. 2 |
Figure 2 (A,B): Adenocarcinoma. The biopsy was performed in the prone position. The cannula can be seen near the 7.9 mm nodule (arrow in A), which was then speared (arrow in B) and multiple cores were obtained.
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| Fig. 3 |
Figure 3 (A,B): Tuberculosis. This patient had multiple lung nodules and had one failed FNAC as well. A 7.5 mm nodule in the right lower lobe was selected (arrow in A) and was successfully speared by the cannula (arrow in B).