NCAM1 and neoplasm: Occasional patients lack CD56 expression (i.e., a cytotoxic T-cell phenotype).[4] This tumor is thought to derive from the malignant transformation of mature NK cells or post-thymic T cells.[5] Extranodal NKTL, nasal type, accounts for 1% of all lymphomas in patients of European descent, and the incidence is higher in Asian, South American, and Hispanic peoples.[2] NKTL is an aggressive extranodal tumor with often rapid and fatal evolution.[4] A favorable outcome is only achieved with early diagnosis and treatment, but it is not always easy to recognize NKTL.