Cutaneous Lymphadenoma Is a Distinct Trichoblastoma-like Lymphoepithelial Tumor With Diffuse Androgen Receptor Immunoreactivity, Notch1 Ligand in Reed-Sternberg-like Cells, and Common EGFR Somatic Mutations

The document discusses Cutaneous Lymphadenoma, a unique trichoblastoma-like lymphoepithelial tumor. The study, which analyzed 11 cases, found that this tumor exhibits diffuse androgen receptor immunoreactivity, Notch1 ligand in Reed-Sternberg–like cells, and common EGFR somatic mutations. The tumor cells were also found to be positive for hair follicle stem cell markers CK15 and PHLDA1. The study suggests that the EGFR gain-of-function somatic mutations may provoke a continuous hair follicle stem cell proliferation state and block entry into the catagen phase, which together with the Notch pathway stimulation, may be responsible for cutaneous lymphadenoma tumor growth. The study received support from Instituto de Salud Carlos III, Spain, and FEDER European funds.