The examination of the atrio-ventricular node region should be a routine practice in all cases of sudden unexpected death in infancy (SUDI) and childhood (SUDC).

key pointsTo describe 3 pediatric cases in which the sampling of the atrioventricular (AV) node was crucial to identify the cause and/or mechanism of death. We also describe 6 other pediatric autopsy cases with a non-cardiac cause of death in which cartilage was present in the fulcrum, adjacent to the AV node. We routinely sample the AV node region in cases of SUDI and SUDC. This experience provides the authors with a comprehensive understanding of regional normal histological variation. Samples are stained with H&E, Trichrome, Alcian Blue and S100 immunohistochemistry. In 3 cases features present in the AV node led to the identification of the cause and /or mechanism of death: AV blockade, fibromuscular dysplasia of the AV node artery and acute infarction involving the AV node. In addition, routine sampling of the AV node region indicates that the presence of cartilaginous tissue may be a normal histological feature of the fibrous core tissue adjacent to the conduction system. The presence of abnormal features of the AV node endorses the importance of the routine examination of the AV node region in all autopsies presenting as SUDI and SUDC. In addition, the presence of cartilaginous tissue in the fibrous body (fulcrum) adjacent to the AV node is most likely a variation of normal histology.