title: Reliability of sentinel lymph node biopsy for regional staging of head and neck Merkel cell carcinoma.
abstract: OBJECTIVE
  To determine (1) the reliability of sentinel lymph node (SLN) biopsy and (2) the need for cytokeratin 20 (CK-20) immunostaining in the staging of head and neck Merkel cell carcinoma (MCC).
  
  
  METHODS
  Retrospective cohort study (median follow-up of 34.5 months).
  
  
  METHODS
  Tertiary care center.
  
  
  METHODS
  Ten patients with head and neck MCC who underwent regional staging with SLN biopsy (SLNB) and CK-20 immunostaining.
  
  
  METHODS
  Sentinel lymph nodes were identified using preoperative lymphoscintigraphy, intraoperative gamma probe, and isosulfan blue dye. The SLNs were evaluated with hematoxylin-eosin and CK-20 immunostaining. Patients with negative SLNB results were followed up clinically.
  
  
  METHODS
  Percentage of positive SLNs, regional recurrence in the setting of a negative finding from SLNB, and percentage of positive SLNs requiring CK-20 immunostaining for diagnosis of micrometastatic MCC.
  
  
  RESULTS
  At least 1 SLN was identified in every patient. Of 24 nodes, 19 (79%) were from the neck region and 5 (21%) were from the parotid basin. Two of the 24 SLNs, in 2 (20%) of 10 patients, were positive for metastatic disease. Both positive SLNs appeared negative on hematoxylin-eosin-stained sections, but small foci of micrometastatic MCC were identified with CK-20 immunostaining. No cranial nerve complications occurred. Regional failure in the setting of a negative finding on SLNB was observed in 1 (12%) of 8 patients.
  
  
  CONCLUSIONS
  Biopsy of SLNs represents a safe and reliable technique for regional staging of MCC of the head and neck. It provides pathologists with a limited number of SLNs for focused analysis, which is imperative because hematoxylin-eosin immunostaining is often insufficient for identifying micrometastatic MCC. The use of anti-CK-20 antibody allows accurate identification of micrometastatic MCC.
authors: Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor 48109-0312, USA.
authors: Cecelia E
authors: CE
authors: Schmalbach
authors: Lori
authors: L
authors: Lowe
authors: Theodoros N
authors: TN
authors: Teknos
authors: Timothy M
authors: TM
authors: Johnson
authors: Carol R
authors: CR
authors: Bradford
mesh_terms: D000368:Aged; D015266:Carcinoma, Merkel Cell / Q000473:pathology*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006258:Head and Neck Neoplasms / Q000473:pathology*; D006801:Humans; D008297:Male; D009367:Neoplasm Staging / Q000379:methods*; D012189:Retrospective Studies; D021701:Sentinel Lymph Node Biopsy / Q000379:methods