<prompt> Acanthosis involves-Str spinosumStr granuolosumStr BasaleStr Corneum  <response>: Acanthosis is diffuse epidermal hyperplasia thickening of the skin. It implies increased thickness of the Malpighian layer stratum basale and stratum spinosum. Acanthosis nigricans is often associated with type 2 diabetes, and is usually observed in the back of neck, axilla, and other folded regions of the skin. Ref Harrison20th edition pg 1206 