Background
Hyperkeratosis of the nipple and/or areola (HNA) is defined as excessive keratinization of the nipple and/or areola. Hyperkeratosis of the nipple and/or areola is characterized by hyperpigmented, verrucous or filiform, keratotic thickening of the nipple and/or areola, with a papillomatosis or velvety sensation to touch. Hyperkeratosis of the nipple and/or areola has classically been classified into the following three subsets
:
Type I – hyperkeratosis of the nipple and/or areola due to the extension of an epidermal nevus
Type II – hyperkeratosis of the nipple and/or areola in conjunction with disseminated dermatoses
Type III – Nevoid hyperkeratosis of the nipple and/or areola
Perez-Izquierdo et al suggested an alternative classification, distinguishing two types: (1) those that are idiopathic or nevoid and (2) those that are secondary to other conditions.
Others have advocated that the term “nevoid” be replaced by “idiopathic”.
Upon review of the literature, a recommended classification is into (1) primary hyperkeratosis of the nipple and/or areola, which is idiopathic,
and (2) secondary hyperkeratosis of the nipple and/or areola, which is associated with the following:
Epidermal nevus
Organoid nevus
Leiomyomas
Verruca
Congenital, acquired, or erythrodermic ichthyosis
Malignant acanthosis nigricans
Chronic eczema such as atopic dermatitis
Chronic mucocutaneous candidiasis
Pregnant females
Males receiving hormonal therapy for prostate cancer
Estrogen therapy for androgen insensitivity syndrome
Vemurafenib treatment
Malassezia furfur infection