Assessment of right ventricular lipomatosis by histomorphometry in control adult autopsy cases

A histomorphometry study was carried out to assess the degree of right ventricular lipomatosis in control autopsy cases and to evaluate if this was correlated with parameters such as sex, age, body mass index (BMI) and heart weight. A total of 70 adult cases were selected from cases of violent death between 1991 and 1999 and where autopsies were carried out in the Department of Pathology and Forensic Medicine in Garches. All cases with heart pathology, abnormal BMI or putrefaction were excluded. Cases with lung or liver pathology were also excluded. Furthermore, 10 adult autopsy cases who died suddenly of arrhythmogenic right ventricular cardiomyopathy (ARVC) were compared with 10 age and sex-matched control cases. Details on sex, age, BMI and heart weight were obtained from the post-mortem records. For each case one sample of the right front ventricular wall was fixed in 10% neutral saline-buffered formalin and one 5-microm-section was stained with haematoxylin and eosin. The Leica Quantimet 500 analysis system was used for the histomorphometrical study. The mean degree of lipomatosis was measured under blind conditions in the ventricular wall and epicardial fat was excluded. Covariance analysis and the Wilcoxon test were used for statistics. The mean age of the control population was 37.5 years, the sex ratio was 1.9:1 (male:female). The mean degree of lipomatosis was 17.03% and the degree of lipomatosis was significantly correlated with age (p = 0.0029) but not with sex, BMI and heart weight. There was a statistically significant increase in fat in ARVC cases compared with age and sex-matched controls (p < 0.001). Fat infiltration of the right ventricle could be an adipose involution due to an ageing process and heavy fat infiltration can be difficult to distinguish from ARVC. Our study suggests that fat infiltration is not essential for the post-mortem diagnosis of ARVC which also requires fibrosis and degenerating myocytes trapped within areas of fibrosis.