A hereditary skin disease characterized by fish-scale-like desquamation. This condition usually has no subjective symptoms, with skin lesions worsening during the cold and dry winter season and alleviating in the warm and humid summer. Itching and discomfort occur when the skin is dry, and pain is felt when fissures develop. The lesions worsen with age, but after puberty, due to increased secretion from the sebaceous and sweat glands, the symptoms may lessen. Patients often have a family history of the condition, developing it from childhood and lasting throughout their lifetime.