**Splenic Autoinfarction**

**Core Concept**
Splenic autoinfarction occurs due to an imbalance between the splenic blood supply and the splenic demand, leading to ischemia and subsequent infarction. This condition is often associated with the presence of a splenic artery aneurysm or a hypoplastic splenic artery.

**Why the Correct Answer is Right**
Splenic autoinfarction typically occurs in infants and children, particularly those with a congenital splenic artery aneurysm. The aneurysm can compress or thrombose the splenic artery, leading to a decrease in blood flow to the spleen. As a result, the spleen becomes ischemic, and infarction can occur. The aneurysm can also rupture, causing a hemorrhagic infarction.

**Why Each Wrong Option is Incorrect**
**Option A:** Splenic autoinfarction is not typically associated with a splenic vein thrombosis, which would more likely lead to a splenic infarction due to venous outflow obstruction.
**Option B:** While a splenic artery thrombosis can cause an infarction, it is not typically described as an "autoinfarction," which implies a self-contained process without an external cause.
**Option C:** A splenic abscess is a separate entity from splenic autoinfarction, typically resulting from bacterial infection and not an imbalance in blood supply.

**Clinical Pearl / High-Yield Fact**
In infants and children, a palpable abdominal mass may be a sign of a splenic artery aneurysm, which can lead to splenic autoinfarction if left untreated.

**Correct Answer: D. Splenic artery aneurysm.**