Familial acanthosis nigricans with p.K650T FGFR3 mutation.

Acanthosis nigricans (AN) is a pigmentary skin disorder, which may present in association with clinical disorders such as obesity and malignancy. Occasionally, this unique skin manifestation is seen in alliance with several skeletal disorders, such Crouzon syndrome, achondroplasia and hypochondroplasia (HCH). These orthopedic disorders are known to have genetic changes in FGFR3. Recently, AN was reported in HCH with p.K650T mutation in FGFR3, and to date, there are only three reports, comprising 18 cases, describing AN harboring this specific gene mutation. Herein, we detail three new cases of AN with p.K650T FGFR3 mutation, and review the 21 known cases.