What condition is caused by systemic illness and results in nail pitting?

Nail pitting is a condition characterized by small depressions or dimples on the surface of the nails, and it is most commonly associated with psoriasis. Psoriasis is a chronic autoimmune condition that can lead to various skin manifestations, including the health of the nails. When the body's immune system mistakenly attacks healthy cells, it can disrupt nail growth, resulting in the formation of these pits.

The presence of nail pitting typically indicates an underlying systemic issue, particularly related to skin conditions like psoriasis. In this case, the link between psoriasis and nail pitting is well-documented, as the inflammatory processes involved in psoriasis can affect the nail matrix, where nails are formed, leading to these characteristic changes.

While other conditions listed may have various effects on the skin or hair, they do not specifically cause nail pitting related to a systemic illness. For example, melanoma is a form of skin cancer that primarily affects skin pigmentation and does not result in pitting of the nails. Similarly, eczema mainly affects the skin, and alopecia is a condition related primarily to hair loss rather than nails. Thus, psoriasis stands out as the condition that leads to nail pitting as a result of systemic illness.