What term refers to the hardening and thickening of the skin?

The term that refers to the hardening and thickening of the skin is scleroderma. Scleroderma is a chronic autoimmune condition that primarily affects the connective tissues, leading to the abnormal production of collagen. This overproduction results in the skin becoming thick and hardened, often accompanied by changes in skin texture and elasticity. It can also affect internal organs, but its most noticeable symptoms are typically observed in the skin.

This condition is distinct from dermatitis, eczema, and psoriasis, which involve inflammation, irritation, or scaling of the skin rather than the significant thickening and hardening associated with scleroderma. Dermatitis generally refers to inflammation of the skin, eczema involves red, itchy patches, and psoriasis is characterized by rapid skin cell turnover leading to thick, scaly patches. Each of these conditions has a different underlying cause and manifestation, making scleroderma the specific term for skin hardening and thickening.