Which of the following is the pathognomonic histological finding in the placenta of a patient with preeclampsia?

Explanation

## Placental Pathology in Preeclampsia **Key Point:** Acute atherosis of spiral arteries is the characteristic and pathognomonic histological lesion seen in preeclampsia, reflecting the underlying endothelial dysfunction and placental ischemia. ### Acute Atherosis: Definition and Features Acute atherosis is a distinctive lesion of the spiral arteries characterized by: - Lipid-laden macrophages (foamy cells) in the vessel wall - Fibrinoid necrosis of the vessel wall - Acute inflammatory infiltrate (neutrophils and lymphocytes) - Narrowing of the arterial lumen - Absence of atherosclerotic plaques (distinguishing it from true atherosclerosis) ### Mechanism in Preeclampsia In preeclampsia, there is: 1. Failure of trophoblastic invasion of spiral arteries (shallow invasion) 2. Inadequate remodeling of spiral arteries 3. Persistence of high-resistance, low-flow placental circulation 4. Endothelial injury and ischemic placental damage 5. Development of acute atherosis as a consequence of this malperfusion ### Clinical Significance **High-Yield:** Acute atherosis is found in approximately 50–60% of preeclamptic placentas and is associated with: - Severe preeclampsia - Placental insufficiency - Intrauterine growth restriction (IUGR) - Recurrent preeclampsia in subsequent pregnancies **Clinical Pearl:** While acute atherosis is highly suggestive of preeclampsia, it is not absolutely specific and can occasionally be seen in other conditions causing placental malperfusion (e.g., antiphospholipid syndrome, chronic hypertension). ### Other Placental Findings in Preeclampsia - Placental infarction (common but non-specific) - Increased syncytial knots - Villous edema - Reduced placental weight - Increased perivillous fibrin deposition