Brooke-Spiegler syndrome is a rare condition with a predisposition to develop cutaneous adnexal neoplasms, especially cylindromas, trichoepitheliomas and spiradenomas. Malignant transformation of cylindromas is rare. In such cases usually cylindrocarcinomas develop within these lesions. We present an unusual case of basal cell carcinoma developing within a preexisting cylindroma.58-year-old woman with a 30-year history of multiple dermal cylindromas extensively involving her scalp was referred for dermatological treatment. The patient reported that one of the long-lasting lesions, 5.5 cm in size, ulcerated within the foregoing few weeks. Histopathology confirmed cylindromas and basal cell carcinoma within the ulcerating tumor. Surgical excision of largest cylindroma tumors led to cosmetic and functional improvement. Magnetic resonance and computed tomography showed tumor infiltration into the skull lamina externa. Metastases were excluded by chest radiography and abdominal ultrasound examination.Patients with Brooke-Spiegler syndrome should be followed-up for malignant transformation of skin tumors to prevent deep penetration and possible metastases.