Familial acanthosis nigricans with the FGFR3 mutation: Differences of pigmentation between male and female patients.

Familial acanthosis nigricans caused by the mutation of the fibroblast growth factor receptor 3 (FGFR3) gene is characterized by short stature, hypochondroplasia and acanthosis nigricans. We herein report a Japanese family that showed a missense mutation of c.1948A>C (p.K650Q) in FGFR3. The pigmentation of acanthosis nigricans was more prominent in male patients than in female patients in this family. We immunohistochemically analyzed the distribution of melanocytes. Although pigmentation in the basal layer was denser in the proband, there was no difference in the distribution and number of melanocytes.