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Ann Surg Oncol (2012) 19:33043306 DOI 10.1245/s10434-012-2516-y
EDITORIAL MELANOMAS
Is a Merkel Just Like a Melanoma? The Pathologic Analysis of Merkel Cell Carcinoma Specimens
Ryan C. Fields, MD1 and Daniel G. Coit, MD2
1Department of Surgery, Barnes-Jewish Hospital, Washington University School of Medicine, St. Louis, Missouri; 2Gastric and Mixed Tumor Service, Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY
I remember being presented my rst pathology report for a patient with Merkel cell carcinoma (MCC). What caught my attention the most was the absolute lack of detail in the report, which was generated from a leading academic medical center. Were treatment decisions really being made on such rudimentary variables, such as tumor diameter? At the time, however, a busy clinic and the multiple obligations of a surgical fellow pushed the thoughts to the back of my head. Yet that experience was brought back to the forefront of my mind once again only a few days later when our internal review of that Merkel cell cancer specimen was completed. I was now staring at a pathology report with a wealth of descriptive information similar to what a standard melanoma pathology report would include: tumor thickness, ulceration, mitotic count, etc. Now I was thoroughly engaged because I was completely confusedwhat was the important primary tumor data that a clinician should use to make subsequent treatment recommendations in this rare cutaneous malignancy? Do the same variables that are associated with outcomes in melanoma apply a priori to MCC? The idea seems logical enough, given that they are both skin cancers. However, there also are many differences (cell of origin, growth pattern, proliferative index/growth rate, etc.) that might make using the melanoma prognostic factors to risk stratify MCC, such as placing the proverbial square peg in a
round hole; it is entirely possible that the most signicant similarity between melanoma and MCC is that they both start with m.
In melanoma, the American Joint Committee on Cancer (AJCC) stage classication and determination of the prognostic signicance of tumor thickness, mitotic rate, and ulceration is based on an exhaustive analysis of more than 30,000 patients with stage13 melanoma with excellent clinical, pathologic, and follow-up data.1 In contrast, the AJCC staging system in MCC is based on a population-based...