Abnormal Muscularization of Intra-acinar Pulmonary Arteries in Two Cases Presenting as Sudden Infant Death

Abstract

Abnormal muscularization of acinar arteries is the hallmark of persistent pulmonary hypertension of newborn (PPHN), an uncommon disease with high rate of morbidity and mortality. PPHN presents with signs of respiratory distress immediately following birth. We herein report 2 cases presenting as a witnessed sudden unexpected death in the late neonatal period, preceded by respiratory deterioration and in whom the presence of abnormal muscularization of the acinar pulmonary arteries was reminiscent of PPHN. The significance of this report is twofold: to increase the awareness among pediatricians and pathologists of this feature that can present in some cases of Sudden Unexpected Death in Infancy/Sudden Infant Death Syndrome, and to highlight the importance of performing a thorough autopsy in order to identify the abnormality.

Perinatal Pulmonary Hemorrhage: A Retrospective Autopsy Case Series

“…17 Although the factors that lead to persistence of muscularized intra-acinar arterioles are not completely understood, it may represent a response to hypoxia leading to vasoconstriction and ultimately increased vascular resistance. 16 To our knowledge, persistence of muscularized intra-acinar arterioles has not been described in PH, but we hypothesize, based on our findings, that vasoconstriction and increased vascular resistance may contribute to PH. Extensive review of literature (English language in PubMed) was performed, but no definite correlation between placental pathology and PH has been reported to the best of our knowledge.…”

“…Therefore, we included persistence of muscularized intra-acinar arterioles as a histologic sign of pulmonary maldevelopment, particularly since PH can increase lung weight and may mask the presence of underlying pulmonary hypoplasia. Zainun et al 16 recently described 2 infants who presented with sudden death in the late neonatal period, and the main histologic finding was the presence of abnormal muscularization of the acinar pulmonary arteries, similar to the findings classically seen in PPHN. The histological hallmark of PPHN is the muscularization of the small pulmonary arteries with abnormal extension of vascular smooth muscle into the small, normally nonmuscularized intra-acinar arteries.…”

Fatal Deterioration of a Respiratory Syncytial Virus Infection in an Infant with Abnormal Muscularization of Intra-Acinar Pulmonary Arteries: Autopsy and Histological Findings

“…Abnormal muscularization of the intra-acinar arteries has been reported in SUID and interpreted as idiopathic PPHN [ 22 ]. This condition may be due to a prolonged intra-uterine hypoxia with the induction of chronic vasoconstriction of small arteries [ 23 , 24 ].…”