title: Sentinel nodes are identifiable in formalin-fixed specimens after surgeon-performed ex vivo sentinel lymph node mapping in colorectal cancer.
abstract: BACKGROUND
  In recent years, the technique of sentinel lymph node (SLN) mapping has been applied to colorectal cancer. One aim was to ultrastage patients who were deemed node negative by routine pathologic processing but who went on to develop systemic disease. Such a group may benefit from adjuvant chemotherapy.
  
  
  METHODS
  With fully informed consent and ethical approval, 37 patients with primary colorectal cancer and 3 patients with large adenomas were prospectively mapped. Isosulfan blue dye (1 to 2 mL) was injected around tumors within 5 to 10 minutes of resection. After gentle massage to recreate in vivo lymph flow, specimens were placed directly into formalin. During routine pathologic analysis, all nodes were bivalved, and blue-staining nodes were noted. These later underwent multilevel step sectioning with hematoxylin and eosin and cytokeratin staining.
  
  
  RESULTS
  SLNs were found in 39 of 40 patients (98% sensitivity), with an average of 4.1 SLNs per patient (range, 1-8). In 14 of 16 (88% specificity) patients with nodal metastases on routine reporting, SLN status was in accordance. Focused examination of SLNs identified occult tumor deposits in 6 (29%) of 21 node-negative patients. No metastatic cells were found in SLNs draining the three adenomas.
  
  
  CONCLUSIONS
  The ability to identify SLNs after formalin fixation increases the ease and applicability of SLN mapping in colorectal cancer. Furthermore, the sensitivity and specificity of this simple ex vivo method for establishing regional lymph node status were directly comparable to those in previously published reports.
authors.affiliation: Departments of Academic Surgery and Pathology, Cork University Hospital, Wilton, Cork, Ireland.
authors.forename: Fraser McLean
authors.initials: FM
authors.lastname: Smith
authors.forename: John Calvin
authors.initials: JC
authors.lastname: Coffey
authors.forename: Nurul Mod
authors.initials: NM
authors.lastname: Khasri
authors.forename: Miriam Fiona
authors.initials: MF
authors.lastname: Walsh
authors.forename: Nollaig
authors.initials: N
authors.lastname: Parfrey
authors.forename: Eoin
authors.initials: E
authors.lastname: Gaffney
authors.forename: Richard
authors.initials: R
authors.lastname: Stephens
authors.forename: M John
authors.initials: MJ
authors.lastname: Kennedy
authors.forename: William
authors.initials: W
authors.lastname: Kirwan
authors.forename: H Paul
authors.initials: HP
authors.lastname: Redmond
mesh_terms: D000236:Adenoma / Q000473:pathology*; D015179:Colorectal Neoplasms / Q000473:pathology*; D005404:Fixatives; D005557:Formaldehyde; D006801:Humans; D009367:Neoplasm Staging / Q000379:methods*; D011446:Prospective Studies; D012394:Rosaniline Dyes; D012680:Sensitivity and Specificity; D021701:Sentinel Lymph Node Biopsy / Q000379:methods*; D013048:Specimen Handling; D016707:Tissue Fixation
chemical_list: D005404:Fixatives; D012394:Rosaniline Dyes; D005557:Formaldehyde; C025484:iso-sulfan blue