The Origins of Merkel Cell Carcinoma: Defining Paths to the Neuroendocrine Phenotype

Combined Merkel Cell Carcinoma with Nodal Presentation: Report of a Case Diagnosed with Excisional but Not Incisional Biopsy and Literature Review

“…MCC is a rare and aggressive cutaneous neuroendocrine carcinoma with two major etiologic factors: the integration of the Merkel cell polyomavirus (MCPyV) genome into the host cells and the genetic damage from long-term ultraviolet light exposure [3,10,12,13]. MCPyV infection has been reported to be the etiological agent responsible for up to 80% of MCC in Europe [3].…”

Incidental Discovery of Merkel Cell Carcinoma During Mohs Micrographic Surgery for Basal Cell Carcinoma and Squamous Cell Carcinoma In Situ

“…The predominance of SCC over BCC in these metastatic cases may be linked to the observation that MCC co-occurring with SCC is usually not associated with the oncogenic Merkel cell polyomavirus (MCPyV) 4 ; it is well-documented that MCPyVnegative MCC tends to behave more aggressively. 4,5 In addition, emerging evidence suggests shared genetic mutations in keratinocyte precursor cells common to both MCC and SCC. 4,5 By contrast, MCC/BCC collision tumors are less frequently reported as metastatic on presentation.…”

“…4,5 In addition, emerging evidence suggests shared genetic mutations in keratinocyte precursor cells common to both MCC and SCC. 4,5 By contrast, MCC/BCC collision tumors are less frequently reported as metastatic on presentation. Case 1 reported herein represents a rare case of collision tumor with nodal presentation consisting solely of MCC and BCC, adding a 14th case to the existing series 1 and underscoring the unpredictable clinical behavior of these neoplasms.…”

Combined Merkel cell carcinoma and cutaneous squamous cell carcinoma with lymph node metastases: Report of two cases

“…Merkel cell carcinoma (MCC), also known as primary cutaneous neuroendocrine tumor, is an infrequent, aggressive cutaneous neoplasm, that typically affects the photodamaged skin of elderly individuals, and patients with a history of immunosuppression 1–6 . Although the histogenesis of MCC has been the object of considerable debate since its original description, and the cell of origin is still unknown, two distinct subtypes of MCC have now been proposed based on their pathogenesis: one that is related to the Merkel cell polyomavirus (MCPyV), that represents the majority of all cases (with variable percentages, estimated at 80% based on some studies), hypothesized to be of possible dermal (fibroblastic) origin, and another one unrelated to MCPyV infection, that appears to be caused by UV radiation, considered to be of probable epidermal origin (keratinocytic) 1,2,7–9 .…”

“…Merkel cell carcinoma (MCC), also known as primary cutaneous neuroendocrine tumor, is an infrequent, aggressive cutaneous neoplasm, that typically affects the photodamaged skin of elderly individuals, and patients with a history of immunosuppression. [1][2][3][4][5][6] Although the histogenesis of MCC has been the object of considerable debate since its original description, and the cell of origin is still unknown, two distinct subtypes of MCC have now been proposed based on their pathogenesis: one that is related to the Merkel cell polyomavirus (MCPyV), that represents the majority of all cases (with variable percentages, estimated at 80% based on some studies), hypothesized to be of possible dermal (fibroblastic) origin, and another one unrelated to MCPyV infection, that appears to be caused by UV radiation, considered to be of probable epidermal origin (keratinocytic). 1,2,[7][8][9] Because a significant subset of MCC is closely related to UV radiation, it is not unusual for this tumor to be found in close association (as a collision tumor) to other UV-related neoplasms, and this has been reported in the literature with variable frequency.…”