Malignant Cylindroma of Post Aural Region Involving the Temporal Bone.

Dermal eccrine cylindroma is a benign adnexal tumour commonly affecting the neck, scalp and skin of elderly individuals. These are poorly circumscribed dermal or subcutaneous lesions consisting of numerous rounded ovoid or cord shaped dermal island that fit together to form a jigsaw pattern. Malignant transformation is not commonly seen. This case highlights malignant transformation of a dermal eccrine cylindroma in the post aural region extending to involve the underlying mastoid bone.