Merkel cell carcinoma from renal transplant recipients are mostly MCPyV-negative and are frequently associated with squamous cell carcinomas or precursors

Merkelcell.org Summary

This study from France analyzed 15 cases of MCC in which the patients had a history of kidney transplant and thus were taking immune suppressive drugs. The authors found that 10 out of 15 of these MCC tumors were not caused by the Merkel cell polyomavirus (MCPyV). Of the 10 virus-negative MCC tumors, 7 were found to have an adjacent actinic keratosis or squamous cell carcinoma (SCC) component. The authors hypothesize that MCPyV-negative tumors may more often derive from SCC, and that sun exposure may be the primary mechanism of MCC development in kidney transplant patients.

Abstract

Merkel cell carcinoma (MCC), that is primary cutaneous neuroendocrine carcinoma is a rare skin cancer. Main risk factors are UV exposure and immunosuppression. In 2008, Feng et al. identified genomic integration of the Merkel cell Polyomavirus (MCPyV) as the causative agent of about 80% of MCC cases. MCPyV-negative cases were later identified as UV-induced tumours frequently harbouring TP53 and R B1mutations and displaying worst outcome.

A fivefold to 24-fold increased risk of MCC is observed in solid organ transplant recipients (OTR). Moreover, MCPyV- negative MCC has recently been found to predominate in this setting. As we demonstrated that MCPyV-negative MCC can arise from squamous cell carcinoma (SCC), a finding independently evidenced by Harms et al. and given that SCC are the most frequent neoplasms in OTR, we hypothesized that the transformation of SCC towards MCC could constitute the major mechanism of MCC formation in OTR. In this context, the objective of this study was to investigate the predominant aetiology of MCC in kidney transplant recipients.