CYLD and adnexal spiradenoma/cylindroma of a sweat gland: Of note, cases of BCA, principally the membranous subtype, and BCAC have been linked to Brooke-Spiegler syndrome4,5, a rare autosomal dominant condition caused by germline disruption of the tumour suppressor gene CYLD. Brook-Spielger is also associated with skin tumors such as cylindromas, spiradenomas, and trichoepitheliomas, 90% involving the head and neck, with histopathological overlaps between these conditions.