A breast sentinel lymph node protocol revisited: A quality improvement initiative/Revue d'un protocole d'analyse du ganglion sentinelle associe au cancer du sein: une initiative d'amelioration de la qualite

Introduction: At our institution, one H&E level is generated for each breast sentinel lymph node (SLN) block. If this slide appears negative, the SLN protocol (SLNP) is ordered on consecutive levels, consisting of: H&E, CKAE1-AE3, H&E, CKCam5.2, H&E. The purpose of this quality improvement initiative was to evaluate SLNP outcomes and optimize our institutional SLNP. Methods: The number of SLN blocks submitted to a SLNP was determined for 622 specimens from 2018-2019. All slides from SLNP positive blocks were reviewed to determine types of metastases identified and which levels were positive. Results: 1755 of 2104 SLN blocks underwent a SLNP, with 1635 negative blocks (83%) and 120 positive blocks (17%). Of the SLNP positive blocks, there were 52 (43%) isolated tumour cells (ITCs), 47 (39%) micrometastases, and 21 (18%) macrometastases detected. Tumour was highlighted by at least one cytokeratin (CK) stain in all SLNP positive blocks. In 20 of 120 blocks (17%), tumour was only visible on the CK slides. In retrospect, the initial H&E level was positive for tumour in 70 of 120 blocks (58%): 12 ITCs, 37 micrometastases, 21 macrometastases. There were no blocks with tumour visible only on Levels 5-6 of the SLNP. Discussion: Most blocks submitted to the SLNP were negative for tumour. Most positive blocks submitted to the SLNP had metastases on the initial H&E slide. All SLNP positive blocks could have been detected with a SLNP consisting of 2 H&E levels and 1 CK slide. SLNP optimization has financial and laboratory workflow implications. Keywords: Quality improvement, breast carcinoma, sentinel lymph node. Introduction: Dans notre etablissement, une coupe H&E est realisee pour chaque bloc de ganglion sentinelle (GS) associe au cancer du sein. Si la lame est negative, le protocole (PGS) est applique a une serie de coupes consecutives, soit : H&E, CKAE1-AE3, H&E, CKCam5.2, H&E. L'objectif de la presente initiative d'amelioration de la qualite consistait a evaluer les resultats obtenus grace au PGS et a optimiser nos procedures. Methodes: Le nombre de blocs de GS soumis au PGS a ete etabli en fonction de 622 echantillons recueillis de 2018 a 2019. L'ensemble des lames issues des blocs juges positifs suite au PGS ont ete examinees afin de determiner la nature des metastases decelees et d'etablir quelles coupes avaient engendre des resultats positifs. Resultats: Des 2 104 blocs de GS, 1 755 ont ete soumis a un PGS; 1 635 (83 %) se sont averes negatifs et 120 (17 %),