Linear atrophoderma of Moulin (LAM) is an atrophic dermal condition characterized by hyperpigmented, unilateral patches or plaques that resemble atrophoderma of Pasini and Pierini (APP) but that follow Blaschko lines on the trunk or limbs. Onset is often sporadic, mostly occurring during childhood or adolescence. While the exact etiology of LAM is unknown, it may reflect a combination of somatic mosaicism and autoimmunity. No distinguishing risk factors or exposure histories are known.

LAM tends to exhibit a stable, nonprogressive course and typically appears suddenly without preceding inflammation or symptoms.