Utility of cell blocks obtained by catheter aspiration via a guide sheath during endobronchial ultrasonography

Abstract Background The demand for adequate tissue samples for both morphological assessment and molecular studies on lung cancer treatment has increased. The aim of this study was to evaluate whether cell blocks (CBs) prepared from endobronchial ultrasonography with guide sheath (EBUS-GS) rinsing following catheter aspiration provide additional information. Methods We produced CBs from rinse fluid obtained from washing the inside of the sheath with saline after conventional EBUS-GS between May 2012 and April 2013. During the first 7 months, the sheath was aspirated with 20mL of negative pressure while moving the catheter back and forth [aspiration group (Asp)]. During the next 5 months, the sheath was not aspirated, but only rinsed out [conventional group (Con)]. Patients diagnosed with lung cancer by EBUS-GS and/or CBs were identified and evaluated. The diagnostic rate of each sampling method was compared between the two groups. The number of tumor cells was also compared between the CB and EBUS-guided transbronchial lung biopsy (EBUS-TBB) groups. Results EBUS-GS was performed on 113 patients. Fifty-five patients were included in this study (Asp=30, Con=25). The diagnostic yield of CBs in Asp was higher than that in Con (56.7% vs 32.0%; p =0.06). Asp showed no significant difference in the number of tumor cells between CB and EBUS-TBB. One patient who showed negative EBUS-TBB pathological results but positive CB results was diagnosed only by immunohistological staining of CB. Conclusion CB prepared from EBUS-GS rinsing following catheter aspiration may provide additional information.