Primarily expressed in neuroendocrine, natural killer, and T cell lineages [3], aberrant CD56 expression is seen in a variety of hematological malignancies (e.g. multiple myeloma, myelocytic and lymphocytic leukemia) as well as solid tumors (most notably small cell lung cancer [SCLC], Merkel cell carcinoma [MCC], and ovarian cancer) [4–8]. This evidence concerns the gene NCAM1 and Merkel cell skin cancer.