Malignant pilomatricoma is an uncommon malignant follicular adnexal tumor with a predilection for the head and neck among older males. We report the case of a male with an inverted malignant pilomatricoma of the left neck. The initial diagnostics and the treatment pointed to carcinoma of unknown primary (CUP syndrome). The preoperative diagnostic tests included ultrasound examination, CT scan and fine-needle aspiration cytology. However, the preoperative diagnostics did not provide any further information, leading to doubts concerning the initially proposed diagnosis. Histology of the resected tumor revealed a malignant pilomatricoma. We report the clinical presentation and the management of this case and discuss the clinical and histological findings.