INTRODUCTION: One of the most poorly understood areas for TBNA targets is the A-P window. A common misperception is that this area is too dangerous to attempt TBNA given large vascular structures bordering the region. The fear is unsupported as few reported complications from TBNA other than small bleeding at the puncture site exist.1 We report a case utilizing TBNA with an extended length needle in combination with fluoroscopic guidance and successful sampling of the lateral A-P window.
CASE PRESENTATION: A 47 year-old male with a 40 pack/year smoking history was referred for diagnosis of a PET positive A-P window lymph node (fig 1.a, 1.b). Although there were several areas within the A-P window that contained lymph nodes, the PET scan only showed activity in the lateral portion of the A-P window (fig 1.a, 1.b). Additionally, the patient had severe bilateral emphysema (fig 1.c). TBNA of the A-P window was the procedure of choice given the high risk for pneumothorax from transthoracic needle biopsy. Several conventional TBNA attempts were made in the A-P window station without diagnostic material. After failing to reach the lateral lymph node with a standard 1.5 cm TBNA needle, an extended length Vizishot transbronchial needle made by Olympus was used at the same site under fluoroscopic guidance to direct the needle tip to the most lateral area of the A-P window (fig 2). This specimen was positive for malignant cells. In this case, we were able to secure the diagnosis of non-small cell carcinoma with minimal risk to the patient.
DISCUSSIONS: The case above illustrates important issues regarding TBNA of the A-P window, including techniques for sampling even the most lateral areas of the A-P window. With conventional bronchoscopic needles, the lymph nodes immediately adjacent to the left tracheal wall are most likely sampled when performing TBNA in the A-P window. Using ATS nomenclature, these lymph nodes are considered left paratracheal lymph nodes while lymph nodes lateral to the ligamentum arteriosum are considered “true” A-P window lymph nodes. We propose a practical, conceptual framework to optimize TBNA strategies and increase the yield at this station. As such, the A-P window would be divided into thirds: the medial, middle, and lateral sections. While the medial and middle thirds may be sampled with conventional 1.5 cm needles, the most lateral section is completely inaccessible when approached through the tracheal wall. With an extended length needle and fluoroscopic guidance, this area is now available for aspiration. While endobronchial ultrasound (EBUS) is capable of sampling the A-P window, and the same extendable Vizishot needle is used with the EBUS bronchoscope, the angle of penetration is not 90 degrees as is often needed to access the lateral A-P window. The aorta often blocks a 45 degree angle approach to the lateral A-P window. As was shown in the earliest flexible needle TBNA reports, yet rarely used since, an extended length “telescopic” needle is an effective tool for TBNA.2.
CONCLUSION: Often, diagnosis of A-P window lymph nodes can be the determining factor for whether a patient is a surgical candidate. In some patients, the risk for diagnostic procedures other than TBNA can be quite high. Improving our understanding of this lymph node station and the techniques to safely and successfully perform TBNA in the A-P window may have a significant impact on quality of care for our patients.
DISCLOSURE: Daniel Kim, No Financial Disclosure Information; No Product/Research Disclosure Information