A middle aged man presents with paraesthesia of hand and feet. Examination reveals presence of ‘Mees’ lines in the nails and rain drop pigmentation in the hands; The most likely causative toxin for the above mentioned symptoms is :
**Core Concept**
Mees' lines, also known as Mee's white lines or leukonychia striata, are white bands that appear on the fingernails or toenails due to injury or disease affecting the nail matrix. Raindrop pigmentation is a type of skin discoloration characterized by small, rounded, and darkly pigmented spots. These symptoms are often associated with heavy metal poisoning.
**Why the Correct Answer is Right**
The most likely causative toxin for the above-mentioned symptoms is arsenic. Arsenic exposure can cause a range of skin and nail abnormalities, including Mees' lines and raindrop pigmentation. Arsenic toxicity affects the nail matrix, leading to the formation of Mees' lines, and can also cause skin pigmentation changes, including raindrop pigmentation. Arsenic exposure can occur through contaminated water, food, or air.
**Why Each Wrong Option is Incorrect**
**Option A:** Lead poisoning can cause various neurological and gastrointestinal symptoms but is not typically associated with Mees' lines and raindrop pigmentation. Lead exposure can cause skin pigmentation changes, but these are usually macular and not raindrop-like.
**Option B:** Mercury poisoning can cause a range of symptoms, including neurological and renal dysfunction. However, Mees' lines and raindrop pigmentation are not commonly associated with mercury exposure.
**Option C:** Copper poisoning can cause a range of symptoms, including gastrointestinal and neurological dysfunction. However, Mees' lines and raindrop pigmentation are not typically associated with copper exposure.
**Clinical Pearl / High-Yield Fact**
Mees' lines and raindrop pigmentation are characteristic signs of heavy metal poisoning, and a high index of suspicion is necessary to diagnose and treat these conditions promptly.
**Correct Answer:** A. Arsenic.