Lymph Node Metastasis With Both Components of Combined Cutaneous Squamous Cell Carcinoma/Merkel Cell (Neuroendocrine) Carcinoma.

To the Editor: Merkel cell carcinoma (MCC) is an infrequent primary neuroendocrine cutaneous tumor with aggressive behavior. The risk of MCC is increased 66– 182-fold in organ transplant recipients and tends to appear at a younger age.1 MCC can be found in combination with other tumor types, mainly squamous cell carcinoma (SCC),2–8 and in single reports with basal cell carcinoma (BCC),9 glandular epithelial carcinomas and of sarcomatous differentiation.3,10 A biphenotypic metastasis of SSC/MCC suggests that this combination in primary tumors is higher than chance. Our work provides new evidence that supports the hypothesis that combined tumors constitute a genetically and immunohistochemically different type of tumor fromMCC.4 To our knowledge, this is the first report of lymph node metastasis with both components of combined cutaneous SCC/MCC.