What is cystic acne, and what is the difference between nodular cysts and acne cysts? Before we get into the differences between the two, let’s talk about what causes cystic acne.

Cystic acne, like most acne, is caused by inflammation. Blackheads and whiteheads are also acne, but they are not inflammatory. 

When it comes to acne vulgaris or "inflammatory acne," the main things that cause pathogenesis (the development of diseases) are hyperkeratinization, the oversecretion of sebum due to androgens, blocked sebaceous glands, and the bacterial colonization of sebaceous units by cutibacterium acnes. All of these factors promote inflammation and the hallmark swelling we see with acne vulgaris. 

Sebaceous glands produce oil or "sebum" in our pilosebaceous unit, a compartment underneath the skin where hair grows. However, with acne, sebaceous glands often produce too much oil. That’s why inflammatory acne is common among oily skin. 

 

What is inflammation? 

Inflammation is your immune’s systems response to threats. As part of the response, your body sends out cytokines, macrophages, and white blood cells to the threatened area. 

Macrophages are actually a type of white blood cell. They surround and eliminate microorganisms. They also remove dead skin cells. 

 

Macrophages continued. What are macrophages? 

Macrophages come to the rescue and help to eliminate the pore-clogging, acne bacteria. However, sebum contains squalene, and squalene can actually transform macrophages into reservoirs for C. acnes bacteria to grow.

Macrophages also produce inflammatory histamines or natural chemicals that make the skin red, swollen, and painful. This inflammation can lead to the production of more oil, and it can make the pores even more congested. 

In response to an overgrowth of c acnes bacteria, macrophages can also react immoderately and provoke an excess of inflammation and subsequent acne scarring.

Within dermatology, “the dysregulation of macrophages significantly influences the severity of inflammatory skin diseases such as acne, psoriasis, and rosacea” (Frontiers in Immunology, 2024).

Furthermore, there are two types of inflammation, acute and chronic. Acute is temporary while cystic acne is the result of chronic inflammation. More simply, inflammatory acne is chronic, meaning it perpetuates itself. Hence, sebum and dead skin cells build up, the cutibacterium acne multiplies, and waste products are formed. Then, there's inflammation, which can ultimately create more sebum.

 

What is nodular acne? What are pitted scars?

Nodular acne is a severe kind of inflammatory acne. It happens underneath the skin.  A nodule is a hardened cyst. Nodules are filled with oil and dead skin cells that have been hardened and hyperkeratinized. The nodule can rupture the follicle, and spread to the surrounding area.

This is what can cause a layer of inflamed, infected tissue to surround it. Nodules need treatment from a dermatologist, and without treatment, they can persist for weeks or even months.

Photocred: Getproactive

If the body quells the swelling and infection, nodular acne will leave scars. It can scar the follicle, the skin cells around it, and it can also degrade the collagen around it, which is why you’ll see pitted scars.

 

What is the difference between an acne cyst and a nodule? 

An acne cyst is a small “sac” beneath the skin. Within the sac, there is an excessive build-up of sebum, bacteria, and dead skin cells too. Because acne cysts are filled with residue, this makes them softer, and they will eventually form a head. Then, the materials will surface onto the skin. If not treated properly, this process can cause further infection. 

Photocred: Ensoul Medica Clinic

On the other hand, nodules are profoundly embedded into the skin, filled with dead skin cells and oil, and can cause considerable scarring. 

 

Acne conglobata

Acne conglobata is a rare and severe form of nodulocystic acne. “It usually presents with tender, double or triple interconnecting comedones, cysts, inflammatory nodules, and deep burrowing abscesses on the face, shoulders, back, chest, upper arms, and thighs" (NIH, 2023). The cysts commonly present in groups of three, and the cysts often rupture a great excess of material onto the skin. 

What treats cystic acne?

Cystic acne requires customized treatment from a dermatologist.  In some cases, dermatologists will remove the cysts or open them in addition to prescribing medication to quell the infection.

Most commonly,  the dermatologist may prescribe antibiotics such astetracyclines, doxycycline, or minocycline. They may also prescribe tretinoin, which helps the skin to rapidly speed up its shedding process by binding to certain receptors. It can also train the skin to do this more quickly on its own. This can be especially helpful for cystic acne since it is deep within the skin.

In regards to scarring, tretinoin, chemical peels, lasers, or radiofrequency are common treatments as well.

Cover photo cred: Dr. Michelle Ross

Sources:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8949596/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10972966/#:~:text=Macrophages%20serve%20as%20a%20pivotal,frameworks%2C%20and%20emergent%20therapeutic%20avenues

https://www.ncbi.nlm.nih.gov/books/NBK459219/#:~:text=Initially%2C%20the%20nodular%20lesion%20may,with%20this%20type%20of%20acne

https://www.ncbi.nlm.nih.gov/books/NBK459173/

https://www.ncbi.nlm.nih.gov/books/NBK459219/#:~:text=Initially%2C%20the%20nodular%20lesion%20may,with%20this%20type%20of%20acne

https://www.ncbi.nlm.nih.gov/books/NBK459173/#:~:text=The%20gradual%20accumulation%20of%20keratinous,subsequent%20nodule%20formation.%5B19%5D

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11082307/