LAUSR

Whilst many sudden death pathologies at autopsy are obvious (e.g. coronary thrombosis, myocardial infarction), a significant number of cases have no overt cause of death. These cases are usually examined by general autopsy practitioners with some histology sampling. Generally, one or two random pieces of cardiac/ventricular tissue are taken to exclude microscopic infection changes, myocarditis, cardiomyopathy and degenerative conditions (e.g. Anderson–Fabry disease). In over 6500 autopsies and 900 referred heart cases, we have found seven cases of the cystic atrioventricular node tumour (CAVNT) and have given this as the cause of death. Given that this lesion is mostly not visible macroscopically at autopsy, we would propose that such ‘unclear’ cases always undergo sampling of the atrioventricular node (AVN) to exclude the CAVNT, together with any ventricular samples of myocardium, and other tests as deemed reasonable. CAVNT shows a wide age range at diagnosis (birth to 95 years, mean age 38) with a female predominance. Characteristically found in cases of sudden death, the mode of death is likely dysrhythmic, due to interference of normal cardiac conduction. Antemortem clues may include heart block, syncope and palpitations. Some cases have implanted pacemakers. Rarely, CAVNT may be seen on transoesophageal echocardiogram, cardiac magnetic resonance imaging or computed tomography. The CAVNT is a lesion sited at the AVN, at the base of the atrial septum or apex of the triangle of Koch. The CAVNT ranges in size from 3 to 30 mm and is rarely evident or easily overlooked on gross examination. The CAVNT is considered to be endodermal heterotopia, resulting from endodermal tissues misplaced during embryonic development (cardiac looping), perhaps reflecting an altered gene function responsible for embryological tissue migration. The CAVNT is debatably not a neoplasm in the classical sense, although this area remains controversial. Histologically, the CAVNT shows variably sized epithelial (columnar, squamous or transitional) lined cysts with a surrounding fibroblastic stroma. No features of invasive malignancy should exist and mesothelial markers should be negative. Our cases comprised the following: