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Merkel cell carcinoma (MCC) is an aggressive neuroendocrine carcinoma of the skin with high rates of metastasis and death. It was first described by Cyril Toker in 1972 who called it trabecular carcinoma. Later, it was named after the Merkel cells (specialized pressure receptor cells in the epidermis) as these are histologically and immunophenotypically like MCC tumor cells. MCC is most common in the 7th to 9th decades of life and frequently arises on chronically sun-exposed skin of the head and neck (>40%). Immunosuppression is also a risk factor with higher rates in patients with hematological malignancy, HIV, and iatrogenic immunosuppression.

Development of MCC follows two distinct pathways: Infection with the Merkel cell polyomavirus (approximately 80% of cases but this varies geographically), or somatic mutations caused by chronic UV exposure. The distinct pathogenic pathways have led some authors to believe that MCC represents two distinct entities based on their etiology. The cell of origin may be keratinocytes, fibroblasts, or B lymphocytes rather than native Merkel cells.

Surgical excision is the first-line treatment, yet there is no clear consensus on the size of the excision margin.


MCC grows as a painless nodular lesion, with a blue or red tinge. Typically, it presents abruptly and explodes into a rapidly growing tumor (Fig. 12.1). Other rapidly growing dermal tumors are in the clinical differential such as lymphoma, amelanotic melanoma, metastatic disease, or sarcoma.


MCC presents as a rapidly enlarging dermal mass.

Heath et al. introduced the helpful mnemonic AEIOU as an aide to the clinical diagnosis1: Asymptomatic, Expanding rapidly, Immunosuppression, Older than 50, UV exposed site.

Nodal disease is seen in up to 80% of head and neck cases at presentation. Checking clinically for nodes at the time of examination can be a helpful differentiator from basal cell carcinoma (BCC). Generally, MCC patients should undergo a staging PET/CT scan. Presentation at a multidisciplinary meeting (MDM) to discuss treatment options prior to surgery is also prudent.


Complete surgical excision is the therapy of choice, and margin control surgery (MCS) can guide the extent of the excision. All patients with resectable disease and who are fit for surgery may be offered one of the two following plans:

Less-Advanced Tumors

MCS of primary MCC under local anesthetic.

If the lesion turns out to be small, the wound can be reconstructed on the same day under local anesthetic. MCC MCS often requires multiple levels and may take all day to get an adequate radial clearance, so general anesthetic is not ideal. However, if it turns out intraoperatively that the MCC is deeply invasive (e.g., with invasion ...

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