Nodular fibromuscular villous stromal dysplasia (NFMVSD): forensic insights into fetal/neonatal outcomes

Objective. To assess the frequency, morphological features, and perinatal/forensic relevance of nodular fibromuscular villous stromal dysplasia (NFMVSD) in a large retrospective placental series.

Methods. Placentas examined between 2014-2018 were retrospectively reviewed. Cases fulfilling diagnostic criteria for NFMVSD were re-evaluated macro- and microscopically, with smooth muscle actin and desmin immunostains when required. Placental weight centiles, lesion distribution, associated abnormalities, and pregnancy outcomes were recorded.

Results. NFMVSD was identified in 27 placentas (1.34%), mainly involving second-/third-order villi with multifocal nodular growth. Sixty-three percent were below the 25th weight percentile. Common findings included hypoxic distress (55%), stem vessel sclerosis (39%), and villous immaturity or dysmaturity (42%). Two intrauterine deaths (6%), four neonatal deaths (14%), and congenital anomalies (32%) occurred.

Conclusions. NFMVSD represents a distinct placental lesion with medicolegal significance, often associated with low placental weight, vascular changes, and hypoxic features. Its recognition may help clarify unexplained fetal or neonatal deaths. Standardized criteria and multicenter studies are required to refine its clinical and forensic implications.