CD9 and Cowden disease: Intraepithelial lymphocytes express the natural killer Tlymphocyte receptors NKG2D and CD9/NKG2A during the pathogenesis of CD, which detects products of the stress-induced genes and Human Leukocyte Antigen E (HLA-E) protein released from the epithelial cell surface.2 The upregulation of natural killer (NK) receptors on epithelial cells is aided by cytotoxicity.2 The creation of a complete pathological CD lesion appears to need both lamina propria (adaptive) and intraepithelial (innate) immune responses, although it is unclear how these 2 processes interact.2