| Darier disease | Acneiform lesions on the chest, back, scalp, neck, and forehead; hyperkeratosis of the nipples possible; histology shows dyskeratosis and acantholysis |
| Nevoid hyperkeratosis | Unilateral or bilateral, diffuse, verrucous thickening and brown pigmentation of the nipple and/or areola; typically no erythema, induration, or discharge from involved area; histology commonly shows hyperkeratosis and papillomatosis |
| Paget disease of the breast | Disorder of nipple-areola complex that commonly leads to pruritus, burning, and/or eczematous changes; often associated with in situ or invasive carcinoma; histology may show a neoplastic process with disarray of cellular architecture |
| Seborrheic keratosis | Sharply demarcated plaques or papules; histology shows basaloid cell acanthosis and no papillomatosis |