Laugier-Hunziker Syndrome

Etiology

The most plausible mechanism for this syndrome is the presence of altered melanocytes in the epidermis.[4] The description is that of L-3,4 dihydroxyphenylalanine reactive melanocytes seen as large dendritic melanocytes. These cells are then capable of increasing melanogenesis.

Epidemiology

Laugier-Hunziker syndrome has more frequently been reported in the Asian population and displays a higher incidence in the Chinese population.[5][6] Cases have also been reported in European regions such as France and Italy. Based on gender predilection, a significant female preponderance has been described. Familial cases usually follow autosomal dominant as well as recessive traits, while sporadic cases are not uncommon.[6][7]

Histopathology

Histopathology of lesions shows increased pigmentation in the basal layer with a few dermal melanophages. Electron microscopy reveals multiple mature melanosomes within keratinocytes and melanophages.[4]

History and Physical

There have been juvenile and adult cases that carry specific disease presentation features but show increased severity in adult form. Juvenile cases have been reported between the ages of 10 and 22 years, while most adult cases are seen between 43 and 55 years of age. The unique features are better described according to the sites affected. Mucosal involvement is characterized by well-defined light brown to brown-black macules, usually 0.1 to 0.5 cm in size, over the oral and genital mucosa. Oral lesions are present over labial mucosa, buccal mucosa, hard palate, tongue, and posterior pharyngeal mucosa while genital lesions are seen on the glans and shaft of the penis in males and vulva in females. A few cases of isolated tongue pigmentation have been reported. Acral or cutaneous involvement manifests as sharply marginated light brown to black lenticular macules and patches approximately 0.5 to 1.5 cm in size, specifically seen over distal two-thirds of all digits of the upper limb and bilateral plantar surfaces (see Image. Laugier-Hunziker Syndrome). Besides this, the lesions extend dorsally by involving the medial and lateral borders of digits.[2][8]

Nail involvement is seen in two-thirds of cases and can be divided into 4 types based on the extent of pigmentation:

• Single 1 to 2 mm longitudinal streaks
• Double 2 to 3 mm longitudinal streaks on the lateral parts
• Homogenous pigmentation involving radial or ulnar half
• Complete pigmentation

However, 1 or all types may be seen in the same patient. One striking feature of nail involvement is nail fold pigmentation, termed pseudo-Hutchinson’s sign.[9] Rare reports of varied pigmentation include isolated tongue pigmentation, conjunctival pigmentation, neck and trunk pigmentation, and diffuse pigmentation, while the common finding of oral and acral involvements is more commonly encountered.[10][9][3][11][12]

Evaluation

Owing to the insidious, although asymptomatic nature of Laugier-Hunziker syndrome, delayed attendance years after onset is usually seen. A thorough history and clinical examination for signs of fatigue, weight loss, gastrointestinal involvement, and drug intake are necessary.

Testing to be performed to exclude other conditions include:

• Corticotrophin/adrenocorticotrophic hormone
• Serum cortisol
• Electrolytes
• Liver function tests
• Endoscopy
• Colonoscopy
• Ultrasound
• Thyroid function test
• HIV testing
• Radiographic barium studies[5] 

Recent reports of associated malignancies have suggested cancer screening, particularly in adult cases.[13]

Treatment / Management

The goal of therapy is purely cosmetic in cases of Laugier-Hunziker syndrome. Treatment options include cryotherapy, Q-switched Nd:YAG laser, Q-switched alexandrite laser, erbium:YAG laser, CO2 laser, and diode laser.[14][15][16](A1)

Differential Diagnosis

The differential diagnosis and their differentiating features include:

• Addison’s disease: Described as primary or secondary results from inadequate levels of adrenocorticotrophic hormone. Primary Addison disease results in hyperpigmentation, which is described as more generalized, with a predilection for sun-exposed areas and recent scars. A few reports of coexistent vitiligo have been described. Cutaneous lesions seem to precede systemic features of fatigue, lethargy, myalgia, nausea, personality changes, and hypotension.
• Peutz-Jeghers syndrome: An autosomal dominant condition characterized by intestinal polyposis and increased susceptibility to malignancies. Mucosal pigmentation differs from Laugier-Hunziker syndrome by crossing the vermilion border. Nail pigmentation is not seen in Peutz-Jeghers syndrome.
• McCune-Albright syndrome: Manifests with café-au-lait macules and not lentiginous lesions, as seen in Laugier-Hunziker syndrome. Other features are polyostotic fibrous dysplasia and precocious puberty.
• Cronkhite-Canada syndrome: This sporadic disorder manifests with gastrointestinal polyposis, anosmia, and dysgeusia. Hyperpigmentation is described with more proximal involvement (arms, legs) than in Laugier-Hunziker syndrome.
• Lentiginosis profusa and Leopard syndrome: Autosomal dominant syndrome characterized by multiple lentigines, hypertelorism, deafness, and cardiac conduction defects.
• Carney syndrome: An autosomal dominant syndrome comprising of lentiginous pigmentation, endocrinopathy, and malignancies.
• Bandler syndrome: Hyperpigmentation resembles Laugier-Hunziker syndrome; systemic involvement is seen as intestinal vascular malformations.
• Acquired immunodeficiency syndrome (AIDS): A diffuse hyperpigmentation may develop in advanced cases.

Other disorders include lichen planus, Smoker’s melanosis, Benign racial pigmentation, melanonychia striata, post-inflammatory hyperpigmentation, Nutritional deficiency (vitamin B12 and folate), and heavy metal poisoning (lead, arsenic, mercury, gold, bismuth, and silver).[17][18][19] Generalized hypermelanosis can be seen with minocycline, phenothiazine, antimalarials, zidovudine, amiodarone, oral contraceptives, clofazimine, and chemotherapeutic agents. Disorders that display the pseudo-Hutchinson sign include Peutz-Jeghers syndrome, subungual hematoma, Bowen disease, and AIDS, while the true Hutchinson sign is specific to melanoma.

Prognosis

The pigmentary lesions of Laugier-Hunziker syndrome usually respond poorly to therapy, and recurrence is high. Of particular note is sun avoidance following successful therapy, which has demonstrated lower recurrence rates.[14]