proliferating trichilemmal cyst
Proliferating trichilemmal tumor is a rare large, multinodular, usually benign, tumor that is generally located in the posterior part of the scalp in aged women (over 50 years). It first appears as a painless nodule that later grows into a solid or partially cystic tumor that is mobile over the underlying subcutaneous tissues. It can present ulceration, inflammation or even bleeding and can cause necrosis of the adjacent tissues.