Pitting of nails is seen in :
## **Core Concept**
Pitting of nails refers to the formation of small depressions or pits on the surface of the nails. This condition is often associated with various systemic and local factors, including autoimmune diseases, nutritional deficiencies, and trauma. The underlying cause usually affects the nail matrix, leading to abnormalities in nail plate formation.
## **Why the Correct Answer is Right**
The correct answer, **Psoriasis**, is right because psoriatic nail involvement is a common manifestation of the disease. Pitting occurs due to the abnormal proliferation of skin cells in the nail matrix, which leads to the formation of small pits on the nail surface. This happens because the inflammatory process associated with psoriasis disrupts the normal growth and development of the nail plate.
## **Why Each Wrong Option is Incorrect**
- **Option A: Fungal infection** - While fungal infections can cause nail abnormalities, such as thickening, discoloration, and brittleness, pitting is not a characteristic feature. Fungal infections more commonly lead to onycholysis (separation of the nail from the nail bed) or onychomadesis (shedding of the nail).
- **Option B: Vitamin deficiency** - Vitamin deficiencies, such as zinc or biotin deficiency, can cause nail changes, including brittleness, thinning, or ridging, but pitting is more specifically associated with psoriasis and alopecia areata.
- **Option D: Trauma** - Trauma to the nail can cause various changes, including subungual hematoma, nail loss, or ridging, but pitting due to trauma is less common and not typically seen as a characteristic feature.
## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that pitting of the nails can also be seen in **Alopecia areata**, another autoimmune condition. In fact, nail pitting is one of the extra scalp manifestations of alopecia areata. Therefore, when evaluating a patient with nail pitting, it's essential to consider both psoriasis and alopecia areata in the differential diagnosis.
## **Correct Answer: C. Psoriasis**