**Question:** At autopsy, the cyanide poisoning case will show the following features, except - A. pulmonary edema; B. decreased red blood cells; C. increased blood pH; D. increased white blood cells.

**Core Concept:** Cyanide poisoning is a life-threatening condition caused by the inhibition of mitochondrial cytochrome c oxidase by hydrogen cyanide (HCN) resulting in cellular hypoxia, acidosis, and multi-organ dysfunction.

**Why the Correct Answer is Right:** Decreased red blood cells (option B) is incorrect as cyanide poisoning primarily affects the respiratory system, leading to hypoxia and tissue hypoperfusion. This results in tissue hypoxia, not a decrease in red blood cells.

**Why Each Wrong Option is Incorrect:**
A. Pulmonary edema (option A) is a common feature of cyanide poisoning due to the inhibition of mitochondrial respiratory chain leading to cellular hypoxia, which activates the hypoxic pulmonary vasoconstriction response.

B. Decreased red blood cells (option B) is incorrect as explained above.

C. Increased blood pH (option C) is not correct because cyanide poisoning leads to acidosis due to impaired cellular respiration and respiratory alkalosis.

D. Increased white blood cells (option D) is not accurate as cyanide poisoning does not primarily affect the immune system or cause significant inflammation, leading to increased white blood cell count.

**Clinical Pearl:** In cyanide poisoning cases, it is essential to consider the correct clinical features like pulmonary edema, acidosis, and multi-organ dysfunction, as these are more indicative of the disease process.

**Correct Answer:** D. Increased white blood cells