Acanthosis

Histologically, acanthosis refers to thickening of the epidermis caused by an increased number of cells, particularly in the spinous (prickle cell) layer of the squamous epithelium. This thickening may be accompanied by elongation of the rete ridges—downward extensions of the epidermis—sometimes referred to as enlargement of the rete pegs. The cells involved typically appear well-organized and normal in shape, which helps to distinguish acanthosis from neoplastic changes

Key Histological Features

Increased thickness of the squamous epithelium, especially the spinous layer.mypathologyreport+1
Elongation of rete ridges or pegs.dermnetnz
Cells generally appear normal, without signs of dysplasia or malignancy.mypathologyreport
Often seen in reactive or benign contexts such as chronic irritation, inflammation, eczema, or psoriasis.mypathologyreport
Can also occur in mucosal tissues, not just skin.mypathologyreport

Common Contexts and Associations

Acanthosis is considered a protective response to irritation or inflammation in tissues lined by squamous epithelium.mypathologyreport
When found in association with velvety, hyperpigmented skin changes, it may signal metabolic disturbances (such as insulin resistance) or even be a paraneoplastic sign if it is rapid or extensive, as in acanthosis nigricans.ncbi.nlm.nih+1

Acanthosis should not be confused with acantholysis, which refers to loss of coherence or adhesion among epidermal keratinocytes, resulting in separation rather than thickening.dermnetnz

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Acanthosis

Key Histological Features

Common Contexts and Associations

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