**2. Epidemiology**

The incidence of HA has increased in recent years, but at the same time, imaging techniques have improved, and therefore, this higher incidence might be explained by the better diagnostic techniques nowadays available. Also, in recent years, it seems to be a change in epidemiology, as more cases of HA in male patients are described, particularly in Europe and Asia. This may be caused by an increased incidence of obesity, another recognized risk factor of HA. Moreover, in recent years, more and more cases of malignant transformation of HA have been reported, and this also might be a result of improved histopathological diagnosis.

Although the link between HA and use or oral contraceptive in women of childbearing age is maintained, recent studies have shown other emerging important risk factors such as metabolic syndrome [8].
