Laugier-Hunziker syndrome (LHS) is a rare, benign condition of macular hyperpigmentation of mucocutaneous surfaces and nails. Although a limited number of familial cases have been reported, no putative genetic defects have been identified, and this is generally thought to be an acquired condition. There are fewer than 200 reported cases in the literature, with the highest prevalence among individuals of Northern European descent. Women are also more frequently affected, with a female to male ratio of 2 to 1. This disorder typically manifests in middle-aged adults as gradual and progressive macular pigmentation of mucocutaneous surfaces, often involving the lips and oral mucosa, as well as the nails.

The etiology of this disorder remains unclear. Histopathological examinations of affected individuals suggest a functional alteration of melanocytes, which appear to be activated to continually synthesize higher amounts of melanin in a chronic fashion. However, the initial stimulus that induces this melanocyte activation is unknown.

Recognizing that this syndrome may mimic other pigmentary disorders, it is important to rule out those with potential for malignant transformation or other clinical implications. As a benign condition itself, the macular lesions of this syndrome do not require therapeutic intervention, although treatment may be pursued for cosmesis.