Dermatologists are physicians specializing in the diagnosis and treatment of diseases and tumors of the skin and its appendages. There are medical and surgical sides to the specialty. Dermatologic surgeons perform skin cancer surgery (including Mohs' micrographic surgery), laser surgery, photodynamic therapy (PDT) and cosmetic procedures using botulinum toxin (Botox), soft tissue fillers, sclerotherapy and liposuction. Dermatopathologists interpret tissue under the microscope (histopathology). Pediatric dermatologists specialize in the diagnoses and treatment of skin disease in children. Immunodermatologists specialize in the diagnosis and management of skin diseases driven by an altered immune system including blistering (bullous) diseases such as pemphigus. In addition, there is a wide range of congenital syndromes managed by dermatologists. Physician assistants and nurse practitioners with specialized training or extensive experience in dermatology also work in this specialty.