132. Psoriasis of the scalp This condition can be very difficult to clear, particularly if there are thick scales • 3% salicylic acid in a suitable base and left on for four to six hours or overnight and then washed out with a tar shampoo • Dithranol preparations are effective but will tint blonde or red hair purple • Steroid preparations can be used to control itching
160. Types of eczema Atopic eczema affects mainly the flexor surfaces of the elbows and knees as well as the face and neck. To a variable degree it can affect the trunk as well. Atopic eczema is common, affecting 3% of all infants, and runs a chronic course with variable remissions.
191. Viral infections Herpes simplex The herpes simplex virus consists of two viral subtypes. Type I is associated with lesions on the face and fingers and sometimes genital lesions. Type II is associated almost entirely with genital infections