Pregnancy-associated hyperkeratosis of the nipple: a report of 25 cases.

IMPORTANCE: Reported physiologic nipple changes in pregnancy do not include hyperkeratosis and are expected to resolve or improve post partum. Hyperkeratosis of the nipple and/or areola can develop in the context of inflammatory diseases (such as atopic dermatitis), in acanthosis nigricans, as an extension of epidermal nevus, after estrogen treatment, and/or in nevoid hyperkeratosis of the nipple and areola. We performed a clinicopathologic analysis of cases of pregnancy-associated nipple hyperkeratosis. OBSERVATIONS: Twenty-five cases of pregnancy-associated nipple hyperkeratosis identified during a 5-year period (January 1, 2007, through December 31, 2012) are reported. The lesions were bilateral and involved predominantly the top of the nipple. Lesions were symptomatic in 17 patients (68%), causing tenderness or discomfort, pruritus, sensitivity to touch, and/or discomfort with breastfeeding. Nine patients (36%) experienced symptomatic aggravation only during pregnancy or breastfeeding. The lesions persisted post partum in 22 patients (88%). Histopathologic features were conspicuous orthokeratotic hyperkeratosis, with papillomatosis and acanthosis being mild or absent. CONCLUSIONS AND RELEVANCE: Pregnancy-associated hyperkeratosis of the nipple can be symptomatic and persist post partum. It may represent a physiologic change of pregnancy. The characteristic clinicopathologic features of this disorder allow differentiation from nevoid hyperkeratosis of the nipple and areola. We suggest that this distinctive clinicopathologic entity be called pregnancy-associated hyperkeratosis of the nipple.