Hidradenitis Suppurativa Risk Factors
NOVEMBER 15, 2016
MD Magazine Staff
Hidradenitis suppurativa is a chronic skin disease associated with severe symptoms and complications. Early diagnosis and treatment can improve disease control and overall quality of life. Robert G. Micheletti, MD, discusses the impact of the disease and provides insight on its optimal management.
Robert G. Micheletti, MD: The most common single population of patients with hidradenitis suppurativa (HS) would be women in their 20s. So, we think about HS as affecting people who are post puberty. And patients who are post-menopausal, you typically don’t have hidradenitis or it burns out. These are patients who are often young patients. They’re in their 20s and 30s, more commonly women by a ratio of about 3:1. Some people have suggested that there may be a race or ethnic difference, in a sense that maybe African Americans are more commonly dealing with hidradenitis. But, there aren’t actually data to support that. Typically, the population is women in their 20s, and often people who are obese. About half of patients or more have obesity. About 70% are smokers. We think of smoking and obesity as playing a role in pathogenesis and possibly in follicular occlusion with respect to smoking, and then with friction and follicular rupture as it relates to obesity and skin-on-skin rubbing and friction.
We touched a little bit before about some of the other factors that are important for the pathogenesis, but really, the way I would summarize it would be to say that these are patients with a genetic predisposition. About one-third of patients have a first-degree relative with hidradenitis, and there are some data talking about even specific gene mutations; so, a patient with a genetic predisposition with particular environment factors that are important. These things are issues like we’ve spoken about, smoking and obesity, but also other factors like microbes—so biofilms that are being created by bacteria—inflammation in open areas that are colonized by bacteria, and then individual inflammatory pathways. And this is important for some of the medications that we’ll talk about, so things like TNF-alpha, Th17, and interleukin-1-beta. These are things that have been found to be upregulated in patients with hidradenitis. We think those things are important.
You get into this vicious cycle, where you have a patient who’s perhaps predisposed to having this happen. They have follicular occlusion maybe from smoking or biofilms, and then once that follicular rupture occurs, there’s more bacteria coming in, there’s more inflammation. These pathways are upregulated, and it becomes this vicious cycle with recurrent inflammation, recurrent scarring, and all the other issues that ensue.
When we talk about making a diagnosis, it’s very critical, because if you have a patient who goes undiagnosed, untreated, it does tend to be progressive. We know that we’re pretty good at treating Hurley stage I, or milder hidradenitis, and we can talk about what Hurley stage I means. We’re pretty good at treating that, but for the more moderate or severe disease, successful treatment can be elusive, and often you have to try several things to hit on the right combination. And so, we want to get to the patients early because if we can shut it down before you get that scarring, before you get sinus tract formation, and before you get these other issues coming into play, then you can make a big difference. But, if you let it go, then certainly it can be more difficult.
Men who develop hidradenitis sometimes have more atypical disease. So, when we talk about the locations that are typically involved, sometimes you’ll see in men some atypical locations, some particularly severe diseases more common in men, as well. Occasionally, in very severe patients or patients who have almost an autoinflammatory-type presentation, you’ll see associations between hidradenitis and things like pyoderma gangrenosum and things like ankylosing spondylitis. And so, other rheumatologic or inflammatory conditions are obviously very important. It’s not uncommon to see, sometimes, joint pains or arthralgias during a hidradenitis flare. I’ve even seen patients with small vessel vasculitis appearing during a hidradenitis suppurativa flare. So, the point here is that—and this gets back to the cardiovascular risk and the other things, as well—this is a systemic inflammatory condition in many respects, particularly for patients with more severe disease, where it’s not just the skin that’s a problem, but all of these other things that are ensuing from a chronic inflammatory state that’s really affecting the whole body.
The other thing that I think is relevant to talk about, it’s not necessarily epidemiologically proven as a risk factor, but it’s something that many patients point to as an exacerbating factor: would-be things like friction, shaving, tight clothing, and so, basically, exacerbating symptoms. We tell patients that there are certain deodorants that may be less irritating. They may not be able to shave. They may want to be careful by wearing loose clothing if they’re going to be exercising, and so on, because those things can exacerbate the disease.