Most people wonder if Hidradenitis Suppurativa isn't an apocrine sweat gland disease why does it appear more commonly in the apocrine sweat gland areas?
The Nature of Follicular Occlusion:
Skin fold occlusion is associated with microbiome alterations and subsequent proinflammatory keratinocyte responses. The common areas often associated with HS clinically such as the armpit, inguinal folds, and underneath the breasts are favorable anatomical sites for follicular occlusion because they can easily experience environmental changes. These changes can be in the form of moisture levels, acidity or pH, and microorganism that inhabit the area. For example, an increase in moisture in these areas decreases pH = more acidic environment better environment for colonization of bacteria, proteins, and the release of inflammatory molecules leading to follicular occlusion.
Why does it seem to be more common and possibly more severe in some areas (apocrine sweat gland areas) as opposed to other areas of the body?
The Skin Layers
The skin is composed of an epidermal layer, hair follicles, sebaceous glands, and sweat glands, which can descend into the underlying dermis. Hidradenitis Suppurativa is primarily a follicular occlusion disease with secondary involvement of the apocrine and eccrine glands.
The sebaceous glands are located in the dermis, the middle layer of the skin, and they develop from the epithelial cells of the hair follicle itself (the external root sheath of the hair follicle). Sebaceous glands are the most closely related to hair follicles and are located throughout the entire body. Sebaceous glands are the oil secreting glands of your body, which is why they are also called the oil glands. They are a type of holocrine simple saccular (alveolar) gland and their function is to secrete a substance called sebum. Sebum is a mixture of fatty substances, entire sebum-producing cells, and epithelial cell debris.
Eccrine glands are the most numerous types of sweat glands and are found almost everywhere on the body. These are the true sweat glands in the sense of helping to regulate body temperature. In other words, sweating causes the loss of body heat and thus cools us down on a hot day or when performing strenuous exercise. This is because as the water in sweat evaporates it takes body heat with it. They secrete moisturizing factors such as water, lactate, urea, sodium and potassium to maintain skin hydration. Secreted sweat mixed with sebum on the skin surface forms a moisturizing lipid layer. Recent studies have further demonstrated that sweat glands secrete several antimicrobial peptides, including dermcidin, cathelicidin and lactoferrin, which help to control skin flora and fight skin infections.
Apocrine glands are a subtype of exocrine secretory glands and are found in many locations such as the axillae, areolae, and anogenital region. These glands, unlike the eccrine glands, serve virtually no role in the regulation of body temperature. These are also the glands largely responsible for body smells, as their excretions are converted by skin bacteria into various chemicals we associated with body odor.
The reason Hidradenitis Suppurativa can develop and be more common in apocrine glands areas is because it has the most abundant amount of hair follicles. Follicular occlusions can happen anywhere there are hair follicles, in any part of the sweat gland regions, which is anywhere on the body, with a few exceptions.
Depending on the amount of inflammation and the depth of your Hidradenitis Suppurativa, sweat glands may become irritated or triggered secondarily and can contribute in making things worse, however, they are not the primary role in Hidradenitis Suppurativa. Most people get clogged hair follicles from time to time, but if you have Hidradenitis Suppurativa, your body is overreacting to those blockages and triggering the innate immune signals.
Some researchers believe the inflammatory immune signals come first and the process of follicular rupture and dermal tunnel formation may happen as a secondary response to the inflammatory response. The one thing most researchers can agree on is Hidradenitis Suppurativa has an immune inflammatory response along with follicular rupture.
Read What is HS: Inflammatory/Follicular Occlusion here.
Read more about gland removal and if it's necessary here.
Read about Blackheads and HS here.
Research article link here.
Content in this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay seeking treatment because of something you have read on this website.
Written by Denise Panter-Fixsen
Edited by Brindley Kons