XVIII: Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified

R20-R23: Symptoms and signs involving the skin and subcutaneous tissue

Symptoms and signs involving the skin and subcutaneous tissue cover a group of conditions that can affect any part of the skin or the layer of tissue just beneath it. They may occur due to various reasons such as allergic reactions, infections, environmental factors, or underlying diseases. Common symptoms may include changes in skin color, redness, swelling, itchy skin, hives, or abnormal sensations like numbness, tingling, or prickling. Some conditions could develop gradually over time, while others may appear suddenly. The progression of these symptoms can vary widely based on their cause. While normal function of the skin is usually to protect the body, these symptoms might disrupt this role, and in some cases, may indicate a more serious underlying condition. In general, these symptoms can affect individuals across all age groups.