Sentinel lymph node biopsy

Editor—Among the possible drawbacks of sentinel node biopsy, discussed by Kell and Kerin,¹ is the risk of false positive findings because of reactive lymph node swelling in the biopsy site. Periodic follow up of the sampled lymph node area has become a common practice after sentinel node biopsy, mostly based on palpation and ultrasonography. Swelling of axillary or inguinal lymph nodes reactive to sentinel node biopsy is likely to occur; a reaction in these sites is a common event, even after lesser injuries.

Unfortunately, both palpation and ultrasonography are poorly accurate in assessing enlarged nodes, and false positive reports are likely to occur: fine needle aspiration may help, if positive, but considering that in these cases a greater diagnostic aggressiveness is expected, a false positive assessment might end in further surgical biopsy of the lymph node. A more aggressive surveillance regimen is expected in patients undergoing sentinel node biopsy, as is a higher frequency of false positive reports and unnecessary invasive procedures.

This possible negative effect is rarely addressed in the literature, although it might substantially reduce the benefits of sentinel node biopsy, a technique aimed uniquely at improving quality of life. Studies aiming to show the cost effectiveness of sentinel node biopsy should mainly address quality of life as the end point, and the frequency of invasive procedures to assess false positive findings at periodic follow up should be a variable carefully taken into account.