Reliability of sentinel lymph node biopsy for regional staging of head and neck Merkel cell carcinoma.
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.
Schmalbach
Cecelia E
CE
Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor 48109-0312, USA.
Lowe
Lori
L
Teknos
Theodoros N
TN
Johnson
Timothy M
TM
Bradford
Carol R
CR
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