Thimble pitting of nails is seen in –
**Core Concept**
Thimble pitting of nails is a characteristic physical examination finding associated with specific dermatological conditions. It is characterized by small, pinpoint depressions on the surface of the nail plate, resembling the surface of a thimble. This phenomenon is often seen in conditions that involve nail plate fragility and splitting.
**Why the Correct Answer is Right**
Thimble pitting is commonly seen in psoriasis, an autoimmune skin condition characterized by chronic inflammation and hyperproliferation of skin cells. The nail changes in psoriasis are thought to result from the abnormal growth and maturation of nail cells, leading to nail plate fragility and splitting. The presence of thimble pitting can be a useful diagnostic clue for psoriasis, particularly in patients with nail involvement.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because thimble pitting is not typically associated with conditions that primarily affect the nail bed, such as nail trauma or infections.
**Option B:** This option is incorrect because while certain systemic conditions, such as anemia or hypothyroidism, can cause nail changes, thimble pitting is not a characteristic finding in these conditions.
**Option C:** This option is incorrect because onychomycosis, a fungal infection of the nail, typically presents with changes such as thickening, discoloration, or brittleness of the nail, rather than thimble pitting.
**Clinical Pearl / High-Yield Fact**
When evaluating patients with nail changes, it is essential to consider the underlying cause of the nail abnormalities and to look for other associated skin or systemic findings that may provide clues to the diagnosis.
**Correct Answer:** D.