**Core Concept**
Reye's syndrome is a rare but serious condition that affects the brain and liver, primarily in children and teenagers recovering from a viral infection. It is characterized by the development of encephalopathy and fatty liver degeneration. The histological findings in Reye's syndrome are critical for diagnosis.

**Why the Correct Answer is Right**
The key histological findings in Reye's syndrome include microvesicular steatosis, which is the accumulation of small fat droplets within hepatocytes. This is due to the disruption of mitochondrial function, leading to impaired fatty acid oxidation and subsequent accumulation of triglycerides. The liver appears swollen and pale, with a characteristic "foamy" appearance due to the microvesicular steatosis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not specific to Reye's syndrome. While fatty liver may be a feature of other conditions, the combination of microvesicular steatosis and encephalopathy is characteristic of Reye's syndrome.
**Option B:** This option is incorrect because it refers to macrovesicular steatosis, which is a different histological finding. Macrovesicular steatosis involves the accumulation of large fat droplets within hepatocytes, whereas microvesicular steatosis is characteristic of Reye's syndrome.
**Option C:** This option is incorrect because it refers to a different type of liver damage. Peliosis hepatis is characterized by the presence of blood-filled cysts within the liver, which is not a feature of Reye's syndrome.
**Option D:** This option is incorrect because it refers to a different histological finding. Focal necrosis involves the death of hepatocytes in a localized area, whereas microvesicular steatosis is a more widespread process.

**Clinical Pearl / High-Yield Fact**
Reye's syndrome is often associated with the use of aspirin in children recovering from a viral infection. This highlights the importance of avoiding aspirin use in children with viral infections.

**Correct Answer: B. Macrovesicular steatosis is not characteristic of Reye's syndrome, which is distinguished by microvesicular steatosis.**