Laugier–Hunziker syndrome

Overview

Laugier–Hunziker syndrome (LHS) is a rare, benign, acquired pigmentation disorder characterized by hyperpigmented macules on the lips, oral mucosa, and nails. First described by Laugier and Hunziker in 1970, the condition is non-cancerous and not associated with systemic disease or malignancy. It typically presents in adulthood and is considered a cosmetic concern rather than a medical threat. Although the pigmentation may resemble more serious syndromes such as Peutz–Jeghers syndrome, LHS is purely mucocutaneous and does not involve internal organ anomalies or increased cancer risk.

Causes

The exact cause of Laugier–Hunziker syndrome is unknown. It is considered an idiopathic condition, meaning it arises spontaneously without an identifiable underlying cause. It is not inherited and has no known genetic mutation or familial association. Some researchers suggest it may involve a reactive melanocytic process or pigmentary incontinence, but there is no definitive explanation for its origin.

Symptoms

LHS presents with characteristic pigmentation changes, usually developing gradually over time. Common clinical features include:

• Hyperpigmented macules on the lips – especially the lower lip and vermillion border

• Dark brown to black macules in the oral mucosa – including the buccal mucosa, tongue, and hard palate

• Longitudinal melanonychia – vertical pigmented bands on the fingernails and toenails, often involving multiple nails

• No associated systemic symptoms – patients are otherwise healthy with normal blood tests and organ function

In most cases, the pigmentation is asymptomatic and discovered incidentally or during routine dental or dermatologic exams.

Diagnosis

Diagnosis of Laugier–Hunziker syndrome is clinical and based on the recognition of typical mucocutaneous pigmentary patterns. Important steps in the diagnostic process include:

• Clinical examination – to assess the distribution and characteristics of pigmented lesions

• Medical history – to exclude familial syndromes or systemic illnesses

• Dermoscopy – to evaluate pigmentation patterns in mucosa and nails

• Histopathology (if needed) – biopsy may show increased melanin in basal layer with no atypia or melanocyte proliferation

• Differential diagnosis – includes Peutz–Jeghers syndrome, Addison’s disease, drug-induced pigmentation, and other lentiginous conditions

Treatment

LHS is a benign condition and does not require medical treatment. However, patients may seek intervention for cosmetic reasons. Treatment options include:

• Reassurance and monitoring – most important, as the condition is harmless

• Laser therapy – such as Q-switched Nd:YAG or alexandrite laser, which may reduce pigmentation

• Cryotherapy – has been used with variable results

• Avoidance of triggering agents – though no specific external factors are confirmed, general pigmentary care is advised

Patients should be advised that pigmentation may recur even after successful cosmetic treatment.

Prognosis

The prognosis of Laugier–Hunziker syndrome is excellent. It is a benign, non-progressive condition with no known malignant potential or systemic involvement. Once diagnosed, no further medical treatment or investigations are necessary unless new or atypical features appear. The main concern for most patients is cosmetic, and reassurance about the benign nature of the disorder is usually sufficient. Regular dermatological follow-up is optional but may be helpful for monitoring nail and mucosal changes.