Laugier-Hunziker syndrome (LHS) is characterized by lentiginous hyperpigmentation of the oral mucosa and lips and is a clinical diagnosis of exclusion. It can be accompanied by longitudinal or striary melanonychia and palmoplantar pigment lesions. 

The patient revealed photobiological skin type 2 according to Fitzpatrick, with inspection revealing multiple, sharply demarcated, lentiginous and polygonally configured, brown macules with a maximum diameter of 10 mm of the anterior mucous membrane of the mouth and cheek. Hard and soft palate, gingiva, tongue and external red lips appeared normal. Dermatoscopy showed the lesions as regular, parallel, linear and curvilinear brown stripes. Thumb and index fingers showed multiple, sharply defined, lentiginous brown macules with a diameter up to 3 mm. Dermatoscopy revealed this lesion as brown, homogeneous pigmentation of the furrows and papillary ridges. 

The acrosyringia were not involved. The thumbnails demonstrated melanonychia striata. A negative Hutchinson sign was noted. Other skin and mucous membrane status and the internal examination status were normal.

The histopathology of the buccal mucosal lesion revealed acanthosis, basal hyperpigmentation and subepidermal melanophages, without an increase in melanocytes. Histopathological examination of the left thumb lesion revealed orthohyperkeratosis and acanthosis with individual, properly differentiated melanocytes, without an increase in the number of melanocytes or pigment incontinence.

The diagnosis of LHS was rendered based on the observations and the patient was informed about its benignity. Since the lesions did not cosmetically affect the patient, no interventions were made.

Source: Korsing, S., Boede, M., Ebrahimsade, S. et al. Laugier-Hunziker syndrome. Dermatologist (2021). https://doi.org/10.1007/s00105-021-04845-x