What histological features are indicative of acanthosis nigricans?

Acanthosis nigricans is characterized histologically by specific changes in the epidermis. The primary features include hyperkeratosis, which refers to an increase in the thickness of the stratum corneum (the outer layer of the epidermis), and papillomatosis, which describes an elevation in the surface of the skin due to the proliferation of dermal papillae that can cause a velvety texture. These changes often reflect underlying conditions such as insulin resistance, obesity, or endocrine disorders.

The combination of hyperkeratosis and papillomatosis leads to the classic appearance of the skin lesions associated with acanthosis nigricans, providing a clear diagnostic histological feature. In many cases, this condition is also linked with conditions like diabetes mellitus or malignancies, but the histological features are primarily what distinguish acanthosis nigricans in a laboratory context.

The other options do not reflect the histological features typical of acanthosis nigricans. Thus, the correct choice emphasizes the pertinent morphological changes associated with this skin condition.