Defects in CYLD are the cause of familial cylindromatosis (CYLD) also known as turban tumor syndrome or dermal eccrine cylindromatosis. CYLD is an autosomal dominant and highly tumor type-specific disorder. The tumors (known as cylindromas because of their characteristic microscopic architecture) are believed to arise from or recapitulate the appearance of the eccrine or apocrine cells of the skin that secrete sweat and scent respectively. Cylindromas arise predominantly in hairy parts of the