Does acanthosis (a condition characterized by thickening of the skin) refer to epidermal hyperplasia (an increase in the number of cells in the epidermis)?

From the Guidelines

Acanthosis indeed refers to epidermal hyperplasia, which is a thickening of the stratum spinosum layer of the epidermis due to an increase in the number of cells in this layer. This condition is characterized by an expanded thickness of the epidermis, particularly the prickle cell layer. Acanthosis can be seen in various skin conditions including psoriasis, eczema, and acanthosis nigricans. In acanthosis nigricans specifically, the thickened epidermis appears as dark, velvety patches of skin, typically in body folds like the neck, armpits, and groin. The hyperplasia occurs due to various stimuli such as insulin resistance, hormonal changes, medications, or underlying malignancies that trigger keratinocyte proliferation. Some key points to consider about acanthosis include:

• It is a histopathological term that describes the thickening of the epidermis
• It results from an increase in the number of cells in the stratum spinosum layer
• It can be seen in various skin conditions, including psoriasis, eczema, and acanthosis nigricans
• The hyperplasia occurs due to various stimuli, such as insulin resistance, hormonal changes, medications, or underlying malignancies Understanding acanthosis is important for dermatopathological diagnosis and can provide insights into the underlying pathophysiology of many skin disorders, as discussed in guidelines for the management of skin conditions 1.

From the Research

Definition of Acanthosis

• Acanthosis refers to a type of skin condition characterized by thickening of the epidermis, which is the outermost layer of the skin.
• It is often associated with hyperplasia, which is an increase in the number of cells in an organ or tissue, in this case, the epidermis.

Relationship between Acanthosis and Epidermal Hyperplasia

• According to a study published in The Journal of Investigative Dermatology 2, retinoids can induce epidermal hyperplasia, which can lead to excessive scaling.
• Another study published in Annals of Dermatology 3 found that epidermal hyperplasia was more prominent in retinoid dermatitis compared with irritant contact dermatitis induced by benzalkonium chloride.
• These studies suggest that acanthosis is indeed related to epidermal hyperplasia, as both conditions involve an increase in the thickness of the epidermis.

Characteristics of Acanthosis

• Acanthosis can be characterized by an increase in the number of cells in the epidermis, leading to thickening of the skin.
• It can be caused by various factors, including retinoid use, as mentioned in the study published in The Journal of Investigative Dermatology 2.
• Acanthosis can also be associated with other skin conditions, such as acantholytic dyskeratotic acanthoma, as reported in a case study published in the Journal of Cutaneous Pathology 4.

Distinction from Other Skin Conditions

• Acanthosis can be distinguished from other skin conditions, such as pemphigus vulgaris and pemphigus foliaceus, based on the level of acantholysis and the presence of dyskeratosis, as reported in a study published in the Journal of Cutaneous Pathology 5.
• The study found that acantholysis was limited to the lower epidermis in pemphigus vulgaris, whereas it involved all epidermal layers in Hailey-Hailey disease and Darier disease.