Laugier–Hunziker syndrome in endocrine clinical practice

Summary Laugier–Hunziker syndrome (LHS) is a rare, benign and acquired disorder characterized by hyperpigmentation of the oral cavity and lips along with longitudinal melanonychia. No underlying systemic abnormalities or malignant predisposition is associated with it. In everyday clinical practice, an endocrinologist encounters certain endocrine conditions (e.g. Addison’s disease, McCune–Albright syndrome) that present with, inter alia, mucocutaneous hyperpigmentation. Even though LHS is easily distinguished from endocrine entities mentioned earlier, diagnostic evaluation usually requires skilled and thorough practitioner. Since it is the diagnosis of exclusion, a number of systemic conditions must be ruled out prior to making the final diagnosis. However, its major differential diagnosis is primarily Peutz-Jeghers syndrome, which carries an increased risk of cancer. Here, we report a case of a young woman who was referred to the endocrinologist for diagnostic evaluation of dark-colored lesions of the oral cavity and nails. All performed laboratory tests were within reference range. Endoscopic gastrointestinal evaluation did not reveal neoplastic formations. Owing to an adult-onset, asymptomatic clinical course and negative diagnostic findings, we made a final diagnosis. In this case, target diagnostic evaluation notably reduced the need for additional expensive and invasive procedures and treatments. Learning points: Laugier–Hunziker syndrome is a rare, acquired cause of asymptomatic, benign mucocutaneous hyperpigmentation. Prior to making a final diagnosis, certain medical entities with overlapping clinical features must be excluded. Endocrine conditions that usually present with the hyperpigmentation of the skin and mucous membranes (e.g. Addison’s disease, McCune–Albright syndrome) can be easily ruled out based on clinical and laboratory findings. Its major differential diagnosis, Peutz-Jeghers syndrome is characterized by melanotic macules of the face and mouth, intestinal polyposis and significantly increased risk of different types of cancer, especially gastrointestinal. Anamnesis, physical examination and target diagnostic evaluation reduce the need for additional invasive and expensive procedures and treatment.