Take Your Pick: Skin-Picking Disorder or Prurigo Nodularis?

Ok, I admit, it. I like to pick just like the next person. If something on my skin just doesn’t feel right or if that pimple looks like it’s going to burst, I can’t resist. Believe it or not, but dermatologists are often pickers too. But why do we pick or scratch? There are several factors that drive us to pick including boredom, itch, anxiety/depression, or again, a juicy zit that’s driving you crazy and you know how satisfying it will be to pop it.  Believe it or not, but scratching or picking is a normal, healthy response developed to remove irritants from the skin and to trigger an immune response.  But like anything else, too much of a good thing can be a problem. 

For some, picking their skin is more than just than chasing an occasional pimple or digging a mosquito bite until it bleeds. Skin picking can be a compulsion, meaning that there is an irresistible urge or need to pick and is known as Skin-Picking Disorder (SPD), excoriation disorder or dermatillomania.  SPD is classified as a mental health disorder as a body-focused repetitive behavior under the umbrella of obsessive-compulsive and related disorders.  The cause is not well understood.  Women are more affected than men and its prevalence in the United States is estimated at about 3.5%.  Often people with SPD can have other underlying mental health conditions like anxiety, depression, obsessive-compulsive disorder (OCD), attention deficit/hyperactivity disorder (ADHD) or post-traumatic stress disorder (PTSD).  

SPD can also cause social isolation or lost work productivity and lead to complications like infection, which in severe cases can be life threatening.  Treatment focuses on behavioral and cognitive therapies, N-acetylcysteine supplements and selective serotonin receptor inhibitors (SSRIs). It’s estimated that less than 20% of SPD patients seek medical attention and if they do, they often are misdiagnosed as anxiety or other mental health disorders. SPD can also mimic other skin conditions like prurigo nodularis where scratching is the hallmark of presentation and our next pick. 

Now what about when itch is the driving factor for that need to pick and rub? When this happens, constantly rubbing or picking the skin can lead to itchy bumps, known as picker’s nodules or prurigo nodularis (PN). PN is a chronic primary skin condition, and the cause is unknown, although research suggests it is an interplay between the immune system and nerves in the skin.  PN is different from SPD in that itch is the driving force and often presents with firm, pink papules or nodules that crust on areas easily accessible to scratch, like the arms, shoulders, abdomen and thighs.  You will often see sparing on the back in between the shoulders and many refer to this as the “butterfly sign.”  Like SPD, PN patients often have underlying anxiety and/or depression. The constant itching can also interfere with sleep and then have a ricochet effect on work and personal life. Also like SPD, PN patients often express embarrassment or shame over their skin lesions. This often fuels s desire to avoid showing areas of affected skin and leads to avoidance of interactions with family and friends.  

The diagnosis of PN can be made clinically but a biopsy can also show characteristic changes. Patients with PN may have underlying atopic dermatitis or other conditions that drive itching such as hepatitis, diabetes, kidney or liver problems, cancer or thyroid disorders.  Treatment can be challenging and focuses on controlling itching and addressing any underlying medical problems.  PN lesions can be treated with topicals, intralesional steroids, cryotherapy (freezing) and phototherapy.  Currently, there are two biologic medications approved for treating PN, dupilumab and nemolizumab, and and more therapies are being studied. 

Trotter’s Take: Although we often joke about being self-proclaimed pickers, it’s important to recognize that picking might be a sign of something more serious like SPD or prurigo nodularis.  

Join my podcast with Dr. Shawn Kwatra and as we pick on prurigo nodularis more to create awareness for this challenging skin condition.