The most common association with coarse pitting of nails and onycholysis is-
**Core Concept**
Lichen planus is a chronic inflammatory condition that affects the skin, mucous membranes, and nails. It is characterized by its distinctive "butterfly" rash on the face and can lead to various nail abnormalities, including coarse pitting and onycholysis.
**Why the Correct Answer is Right**
Coarse pitting of nails and onycholysis are common nail manifestations of lichen planus. The condition is thought to result from an autoimmune response, where the immune system mistakenly attacks the nail matrix and plate, leading to inflammation and subsequent nail damage. The nail matrix is responsible for nail growth, and the nail plate is the visible part of the nail. In lichen planus, the nail matrix is inflamed, causing the nail plate to separate from the nail bed, resulting in onycholysis. Coarse pitting occurs due to the disruption of the nail plate's growth pattern.
**Why Each Wrong Option is Incorrect**
**Option A:** Psoriasis is a chronic autoimmune condition that can cause nail abnormalities, including pitting, onycholysis, and subungual hyperkeratosis. However, it is not the most common association with coarse pitting of nails and onycholysis.
**Option B:** Trauma to the nail can cause onycholysis, but it is not typically associated with coarse pitting.
**Option C:** Fungal infections can cause nail changes, including onycholysis and thickening, but are not typically associated with coarse pitting.
**Clinical Pearl / High-Yield Fact**
Lichen planus can also cause oral mucosal lesions, which are often the first sign of the disease. These lesions are typically violaceous and can be painful.
**Correct Answer:** C.