Which of the following is classified as a congenital skin disorder?

Ichthyosis is indeed classified as a congenital skin disorder because it is primarily caused by genetic factors that result in abnormalities in skin cell production and shedding. This disorder leads to dry, scaly skin and is typically present at birth or develops in early childhood. The type and severity of ichthyosis can vary widely, but its classification as a congenital condition stems from its hereditary nature.

In contrast, eczema, acne, and psoriasis are not classified as congenital disorders. Eczema, which is characterized by patches of inflamed, itchy skin, often has triggers related to environmental factors and can develop at any age, although it frequently appears in childhood. Acne is a condition that arises primarily due to hormonal changes and factors affecting the skin's oil production, usually emerging during adolescence. Psoriasis is an autoimmune condition characterized by the rapid growth of skin cells leading to scaling and inflammation, and while it often appears in early adulthood, its precise causes involve a combination of genetic and environmental factors rather than strictly congenital influences.