I. Introduction

It is not uncommon for people with HS to have other medical conditions. Conditions that are associated with HS are called HS comorbidities. We currently know of more than 25 conditions associated with HS (Table 6.1). Some of these associated diseases affect the skin while others affect other parts of the body.

It is important for patients with HS to be screened for other conditions that may be occurring at the same time as their HS.

Keep in mind that treating HS can become more complicated when additional diseases are involved. This is because treating both HS and another condition at the same time requires additional considerations (for example, recognizing potential drug interactions).

This chapter explores some of the more common diseases associated with HS as well as their impact on HS treatment decisions.

II. HS and Physical Conditions

Metabolic conditions. Some of the most well known conditions associated with HS are problems with metabolism, also called “metabolic diseases.” Patients with HS are more likely to have “metabolic syndrome,” which means having three or more of the following conditions: large waist size, high blood pressure, high blood sugar, high triglycerides in the blood, or low HDL (“good”) cholesterol in the blood. Obesity, high cholesterol, and high blood pressure are reported in over half of people with HS. Additionally, kids with HS have even higher rates of metabolic problems compared to adults.

Screening for diabetes, high blood pressure, high cholesterol, and other risk factors for heart disease is an important part of managing HS given that people with HS are at higher risk of having metabolic conditions. When you see your healthcare provider, make sure you are getting checked for these diseases – regardless of your age, sex, or weight.

• Figure 6.1. Severe scarring and crusted
nodules on the back from partially treated
acne conglobata in a patient with HS.

• Figure 6.2. Psoriasis involving the elbow.

Gut conditions. People with HS are at higher risk of having issues with their digestive system, including inflammatory bowel disease (IBD). Two major types of IBD exist: Crohn’s disease and ulcerative colitis. People with IBD often feel tired and have abdominal pain, diarrhea, or blood in their stool. A patient may already have IBD at the time of HS diagnosis, or may go on to develop it later.

Skin conditions If you have HS, you are more likely to have other problems with your skin. The most common skin condition found in people with HS is acne. Acne can present as red bumps, blackheads, or whiteheads on your face, chest, back, or shoulders. HS is one of four conditions that make up the “follicular occlusion tetrad.” In addition to HS, this “tetrad” also includes acne conglobata, which is a severe form of acne with nodules that may drain and cause scars (Figure 6.1); pilonidal disease, or a cyst or tunnel at the top of the buttocks; and dissecting cellulitis, or abscesses on your scalp that may cause hair loss.

People with HS have a higher chance of having (or developing) any of the other three conditions that make up the “follicular occlusion tetrad.” Other skin conditions seen in patients with HS include psoriasis (Figure 6.2) and pyoderma gangrenosum, which presents as painful ulcers with a purple or ragged border (Figure 6.3). If you notice new or different skin problems that you suspect are not HS, be sure to tell your healthcare provider.

Arthritis. Almost half of people with HS have swelling of their joints called “arthritis.” This may occur years after the skin signs of HS appear, and is more likely in men. Two of the more common types of arthritis are spondyloarthritis and rheumatoid arthritis (RA). Spondyloarthritis causes chronic pain of the lower back, ribs, and hips. Common symptoms of RA are morning stiffness as well as pain and swelling of joints, including the fingers, wrists, and feet. About one in 10 people with HS have spondyloarthritis. People with HS are also twice as likely to have RA compared to people without HS. Furthermore, specifically among people with HS, there appears to be a correlation between the likelihood of RA and HS severity. Studies have seen a higher percentage of RA in patients with more severe HS than in those with milder HS.

Polycystic ovarian syndrome (PCOS). Women with HS are twice as likely to have polycystic ovarian syndrome (PCOS) compared to women without HS. PCOS is a disease where women have abnormal periods and may also have cysts on their ovaries. This can lead to difficulty getting pregnant, weight gain, acne, and hair growth on the face, neck, chest, and stomach. Hormone imbalances from PCOS can cause kids with HS to reach puberty too soon, also known as “precocious puberty.” Signs of early puberty include acne, body odor, and hair on the genitals. If you or your child develop any of these signs, contact your healthcare provider.

Sexual dysfunction. HS can cause sexual dysfunction, or problems in a person’s sex life, for both women and men. Over half of people with HS report issues with sexual health, and this can happen for many reasons. HS commonly involves sensitive body areas such as the groin and genitals; in these cases, sex can cause pain and discomfort. If you feel comfortable, discussing your sexual health concerns with your healthcare provider may be helpful.

Eye conditions. Although it is less common, HS can be associated with inflammatory eye disease. This may range from very mild to very severe disease that can cause permanent damage to the eye. Although many forms of eye disease are not very dangerous, the most severe form seen with HS is called keratitis. Symptoms include eye redness, eye pain, and decreased vision. If you experience these symptoms, you should immediately alert your healthcare provider and make an urgent appointment with an eye doctor. If left untreated, keratitis can result in permanent vision loss.

III. HS and Psychological Conditions

Mood disorders like anxiety and depression are at least twice as common among people with HS than among people without HS. These mood disorders are also associated with sexual dysfunction and can have a tremendous impact on quality of life. Just as it is important to discuss your physical symptoms from HS (such as pain and drainage) with your healthcare provider, it is important to also share any emotional symptoms from HS that you are experiencing. Let your healthcare provider know if you have thoughts about harming yourself. Addressing your mental health is a vital part of managing your HS.

IV. HS and Rare Inflammatory Syndromes

Your HS may be just one part of a genetic syndrome causing an overactive portion of the immune system. For example, “PASH” is when a person has pyoderma gangrenosum, acne, and HS. People with HS may also have “SAPHO” syndrome, which stands for Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis. Synovitis means inflammation of the joint space, and osteitis means inflammation of bone. Pustulosis refers to small bumps filled with pus, usually on the hands and feet. Hyperostosis is when ligaments, or the tissues that connect bones to each other, become hard and bone-like. These syndromes are very rare, but important to recognize.

V. HS Associated Conditions and Impact on Treatment Decisions

HS associated conditions may change how your healthcare provider recommends treating your HS. Some HS associated diseases, like psoriasis, can be treated with medications that are also used to treat HS. This means that you may be able to use one medication to treat both conditions. Other times, your HS associated disease may prevent you from using certain types of HS medications. For example, people with inflammatory bowel disease (IBD) should be careful with interleukin-17 inhibitors. Even though these drugs can be useful in treating HS, they can worsen IBD. It is important that your healthcare provider is aware of all your other health conditions so that you can both engage in the decision-making process to choose the treatments that are right for you.