The Hair Erector Muscle: Order and Disorder of This Often Forgotten Structure

The document discussed the hair erector muscle (HEM), highlighting its often-overlooked role in dermatopathology. It described both passive and active disorders affecting HEM, such as its involvement in conditions like keratoacanthoma, hemangiomas, and dermatofibromas. HEM was also noted to participate in various follicular processes and diseases like syphilis and amyloid. Rarely, HEM was affected by myositis, myopathies, and deposit diseases. Additionally, the document mentioned HEM tumors and hamartomatous conditions, including leiomyoma, leiomyosarcoma, and muscle changes in blue nevi and Becker’s nevus. The presentation aimed to compile the disorders of HEM, which were often supplementary to more prominent conditions.