What is the origin of the Merkel cell and Merkel cell carcinoma (MCC)?

Updated: Jan 18, 2019
  • Author: Arjun S Joshi, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

Answer

The origin of Merkel cells is unclear, as they share both epidermal and neuroendocrine features. Research suggests that they may be derived from pluripotential stem cells of the dermis or, as an alternative, from neural crest cells. Cytologic and immunohistochemical data support both contentions.

Merkel cells display paranuclear staining for cytokeratins, which are also found in other neuroendocrine tumors. Osmiophilic granules contain neuropeptide, such as neuron-specific enolase, chromogranins, and synaptophysin. Evidence suggests that Merkel cells communicate with nerve terminals by means of a glutamatergic pathway, implying that they may have a neuroendocrine origin.

The general assumption is that MCC originates from Merkel cells, though this does not appear to be entirely correct. For example, MCC develops almost exclusively in the dermis, whereas the overwhelming majority of Merkel cells are found in the epidermis, a site rarely involved with MCC. Some suggest that the cells of origin may be immature pluripotential stem cells found in the dermis. These stem cells share phenotypic similarities with Merkel cells, though they do not appear to communicate with nerve terminals. It is postulated that these cells may acquire neuroendocrine features during malignant transformation.


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