Acanthosis nigricans can occur due to -
Hyperplasia of stratum spinosum of the epidermis.
Hyperkeratosis → Thickening of Stratum corneum of epidermis (Cornification of epidermis).
Slight basal cell hyperpigmentation.
Increased multiplication of basal cells
Cornification of basal cells
Keratinisation of epidermal cells
All