Acanthosis nigricans, hypochondroplasia, and FGFR3 mutations: Findings with five new patients, and a review of the literature.

Early development of extensive acanthosis nigricans (AN) is a key feature in some patients who have hypochondroplasia (HCH) in association with FGFR3 mutations. We here report regarding five new patients with HCH who exhibited AN, and we compare their characteristics to the eight patients previously described in the literature. In these patients, the AN lesions began in childhood, and they were extensive. These lesions were located on the torso, the abdomen, and the face, in addition to the typical skin fold sites. Other skin lesions were frequently reported: café-au-lait macules, melanocytic nevi, lentigines, and seborrheic keratosis. The Lys650Thr mutation was the predominant reported mutation of FGFR3.