Lipomatous Hypertrophy of Atrial Septum : Introduction

Comments:
Introduction: Lipomatous hypertrophy of atrial septum (LHAS) is a tumor-like, hamartomatous expansion of the atrial septum by an admixture of mature and brown fat.

The interatrial septum is an invagination of the atrial roof and normally contains epicardial fat. The normal septal thickness is variable but is usually < 2 cm when measured above the fossa ovalis. With excess fat deposition, the septal thickness is >2 cm (range 2 to 8 cm) and it is referred to as LHAS. It can become a large mass bulging into the right atrial chamber and mimic malignancy.

This image of LHAS shows mature fat and brown fat (cells with vacuolated cytoplasm) and a few entrapped hypertrophic cardiac myocytes.