Clinicopathological characteristics of head and neck Merkel cell carcinomas.

BACKGROUND There are still controversies about the therapeutic strategies and subsequent outcome in head and neck Merkel cell carcinoma. METHODS Clinicopathological data of 23 Merkel cell carcinomas, 93 cutaneous head and neck squamous cell carcinomas (HNSCCs), 126 malignant melanomas, and 91 primary parotid gland carcinomas were comprehensively analyzed. Merkel cell carcinomas were cytokeratin 20 (CK20)/neuron-specific enolase (NSE)/chromogranin A (CgA)/synaptophysin (Syn)/thyroid transcription factor-1 (TTF-1)/MIB1 immunostained. RESULTS All Merkel cell carcinomas underwent wide local excision. Parotidectomy/neck dissection was performed in 40%/33% cutaneous Merkel cell carcinoma and 100%/100% in parotid gland Merkel cell carcinoma. Five-year recurrence-free interval (RFI)/overall survival (OS) was significantly higher in malignant melanoma (81/80%) than in cutaneous Merkel cell carcinoma/HNSCC. Interestingly, 5-year RFI/OS was significantly higher in Merkel cell carcinoma (61%/79%) than in HNSCC (33%/65%; p < .0001) despite comparable TNM classifications and treatment regimens. There were neither differences of RFI/OS between parotid gland Merkel cell carcinoma and parotid gland carcinomas, nor in the immunohistochemical profile. CONCLUSION Five-year RFI/OS was significantly better in cutaneous Merkel cell carcinoma when compared with TNM classification matched HNSCC. Five-year RFI/OS was comparable in parotid gland Merkel cell carcinoma and other primary parotid gland malignancies. © 2016 Wiley Periodicals, Inc. Head Neck 39: 92-97, 2017.