TTF-1 Positivity in Merkel Cell Carcinoma: The Chosen Clone Matters

To the Editor: I have read with great interest the recently published article by Hughes et al1 describing a case of a combined Merkel cell carcinoma associated with Bowen disease and squamous cell carcinoma that demonstrated strong and significant positivity for TTF-1 by immunohistochemistry, and I would like to make some additional comments. The authors used in this case study the monoclonal anti-TTF-1 antibody clone SP141 and did not explore...