L80-L99: Other disorders of the skin and subcutaneous tissue

L91: Hypertrophic disorders of skin

Hypertrophic disorders of the skin is a group of conditions characterized by the thickening or enlargement of the skin due to an increase in the size of its cells. Common in these conditions is the overgrowth of a skin layer or structure, causing various aesthetic and physical changes on the skin's surface. Such conditions can have various causes, ranging from genetic factors, certain medications, or a response to injuries, such as burns or piercing. Hypertrophic disorders usually present as raised, often rough patches or growths on the skin that might be an irregular shape or size and may differ in color from the normal skin. The course of these disorders is typically slow and gradual, often causing a considerable psychological burden to those affected. The skin, being the main organ affected, can have implications on its functioning, and these conditions occasionally carry potential for malignant transformations.