Laminar necrosis of placental membranes: a histologic sign of uteroplacental hypoxia.

Laminar necrosis of placental membranes (LN), a band of coagulative necrosis at the choriodecidual interphase, is a histologic lesion of unclear pathogenesis that has been reported in placentas from preeclampsia, preterm premature rupture of membranes, and preterm abruption. To better explore other possible correlations of LN, we performed a retrospective case-control study in which data on pregnancy risks and outcomes, neonate conditions, and placental gross, routine microscopic, and selected immunohistochemistry examinations in 52 consecutive cases of LN were compared with 52 gestational age-matched control cases without LN. Maternal hypertensive disorders and combinations of 2 or more maternal, fetal, neonatal, or placental conditions known to be potentially associated with uteroplacental hypoxia were more prevalent in patients with LN than in control patients. By immunohistochemistry, LN areas were positive for complement 9 (marker of necrosis) and negative for active caspase 3 (marker of irreversible apoptosis), nitrotyrosine residues (marker of oxidative stress), and Ki-67 (proliferation marker), thus confirming their necrotic rather than apoptotic nature. However, LN areas were flanked by caspase 3 positivity, and the positivity for nitrotyrosine residues was more pronounced in the decidua and mesenchyme in the same membrane rolls as LN, which indicates a probable role of apoptosis and oxidative stress in the development of LN. Based on these immunohistochemical results and clinicopathologic correlations, we believe LN should be recognized and reported as a hypoxic placental lesion.