What are the symptoms of ichthyosis?

Ichthyosis is a hereditary keratinization disorder of the skin, primarily characterized by dry skin accompanied by fish-scale or snake-skin-like desquamation. These symptoms commonly occur on the extensor surfaces of the limbs and the trunk, particularly prominent on the extensor aspects of the elbows and knees. The severity varies; mild cases may only exhibit dry skin with minimal scaling during winter, while severe cases present with thick,糠秕状 (millet-like) scales up to 3–8 millimeters in thickness, potentially covering most or all of the body. Symptoms may worsen during cold, dry seasons and improve during warm, humid seasons. Additionally, patients may experience palmoplantar hyperkeratosis, brittle nails, sparse hair, and some individuals may feel itching when winter begins. Although ichthyosis does not directly threaten life, it significantly impacts the patient's quality of life and mental health.