Pregnancy-associated hyperpigmentation: Longitudinal melanonychia

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A 32-year-old white woman of Ashkenazi extraction (skin type III) had a longitudinal dark brown streak on the nails of her second and third toes on the right foot during her first pregnancy. The pigmented streaks were uniformly dark brown, 1 to 2 mr:n in width, with sharp borders. Pigmentation of the periungual skin (Hutchinson's sign) was present on the cuticle and proximal nail bed and extended to the proximal and one lateral nail fold. During pregnancy, the patient also noted the development of 15 to 20 brown macules on the anterior aspect oiher torso. The longitudinal melanonychia resolved after delivery and the brown macules on her trunk becamelighter but did not resolve completely. During her second pregnancy, the patient again noted the development of dark brown streaks of the nails of her right second and left third fingers that were 2 and 3 mm wide, respectively (Fig. 1), and on several toenails. She also noted darkening of the macules on her trunk, as well as the development of new macules. These changes were noted during the fifth month of pregnancy. Six months after delivery, the pigmented streaks on the fingernails and two toenails had completely resolved and the macules on her trunk became lighter. A biopsy specimen of a macule on the abdomen was obtained 11 months after delivery. On histologic examination, the epidermis showed elongation of the rete and basilar melanocytic hyperplasia and hyperpigmentation.