Anterolateral leg alopecia is a benign form of nonscarring alopecia confined to the anterior and lateral aspects of the leg. The condition is sometimes referred to as peroneal alopecia, as this patterned alopecia characteristically overlies the course of the peroneal nerve. Although the condition has been documented among women, anterolateral leg alopecia primarily affects men and increases in prevalence with age; its peak incidence arises among middle-aged to elderly men. The condition is thought to be very common, with estimates suggesting a prevalence of greater than 35% among males. That being said, no epidemiological studies of anterolateral leg alopecia have been undertaken in over half a century; while the condition has been recognized for decades, its benign nature has led it to be largely ignored.

The etiology and pathophysiology of anterolateral leg alopecia remain unclear. Although anterolateral leg alopecia and male pattern baldness may occur concurrently, it has been demonstrated that there exists no statistically significant relationship between the two. While it has long been hypothesized that said condition may be occasioned by trauma (such as rubbing), anterolateral leg alopecia lacks the truncated hairs and follicular hyperkeratosis associated with trauma; skin affected by anterolateral leg alopecia is largely unremarkable but for the lack of hair over affected areas. Research has yet to demonstrate any link between anterolateral leg alopecia and atherosclerotic, rheumatologic, or endocrine disorders. Thus, causal factors for anterolateral leg alopecia have yet to be identified.