Although the course of illness may vary, when untreated, skin picking disorder is most often considered a chronic disorder with fluctuations in intensity over time (
2). One study of 29 patients with the disorder found a mean illness duration of 20.1 years (
17), which is similar to the mean duration of 18.9 years reported in another study, with 24 patients (
15). Individuals report that the symptoms of their picking, although waxing and waning in intensity over many years, are essentially unchanged with time. Seeking medical help from a physician is uncommon among individuals who pick their skin (
15). In fact, some studies suggest that less than 20% of skin pickers seek treatment (
9,
15). Individuals with skin picking disorder often report being unaware that viable treatments are available (
15).
Screening in Mental Health Settings
Skin picking disorder occurs with a variety of other disorders, such as major depressive disorder (12.5%–48%), anxiety disorders (8%–23%), and substance use disorders (14%–36%) (
5,
10,
14–
16). Data on age at onset suggest that skin picking disorder generally begins at an earlier age than these co-occurring disorders (
9). A study of 92 individuals with skin picking disorder found that 17.4% used illegal drugs, 22.8% used tobacco products, and 25.0% used alcohol to relieve feelings associated with picking. Additionally, 85.9% of subjects reported anxiety and 66.3% reported depression due to picking (
9). Therefore, clinicians must screen for both skin picking disorder as well as the secondary manifestations of the disorder if treatment of either disorder is to be successful.
Skin picking disorder is often misdiagnosed as either obsessive-compulsive disorder (OCD) or body dysmorphic disorder. Rates of co-occurring OCD are significantly higher in individuals with skin picking disorder (6%–52%) (
5,
8,
11) than rates observed in the community (1%–3%), and reported rates of skin picking disorder among individuals with OCD have ranged from 8.9% to 24.0% (
21,
22), markedly higher than the range of 1.4%–5.4% found in the community (
3,
4). The repetitive motor symptoms of skin picking disorder have some similarities to the repetitive compulsive rituals in OCD. These findings raise the possibility of an underlying common neurobiological pathway, but several lines of evidence suggest that skin picking disorder is distinct from OCD.
Individuals with skin picking disorder are more likely to be female, they report higher rates of co-occurring grooming disorders (such as hair pulling or compulsive nail biting), and they are more likely to have first-degree relatives with grooming disorders (2). Neurocognitive data also demonstrate a distinction between individuals with skin picking disorder (i.e., demonstrating poor motor inhibition) and individuals with OCD (problems with cognitive flexibility) (
2).
Reports have also indicated substantial comorbidity of skin picking disorder with body dysmorphic disorder (
5,
23,
24). One study found that 44.9% of a sample with body dysmorphic disorder met criteria for lifetime skin picking disorder, and 36.9% met criteria for a current disorder (
23). An earlier study found that 26.8% of individuals with body dysmorphic disorder engaged in skin pick secondary to their body dysmorphic disorder (
24). Arnold et al. (
5) found that 11 (32%) of 34 patients with skin picking disorder had co-occurring body dysmorphic disorder. Although there appears to be overlap between skin picking disorder and body dysmorphic disorder, patients with body dysmorphic disorder pick at their skin to improve their appearance (
24), and these individuals would not meet criteria for skin picking disorder if the skin picking is secondary to body dysmorphic disorder. Many individuals with skin picking disorder, however, do not pick their skin because of their appearance and do not meet criteria for body dysmorphic disorder. Several lines of evidence further delimit these disorders. Whereas skin picking disorder is largely a female disorder, body dysmorphic disorder is seen equally in men and women (
24). Individuals with skin picking disorder are less likely than those with OCD to have first-degree relatives with body dysmorphic disorder (
23). Additionally, whereas body dysmorphic disorder has demonstrated good response to serotonin reuptake inhibitors (
24), the response of skin picking disorder to antidepressants has been mixed.
Other grooming disorders, such as trichotillomania, are common in individuals with skin picking disorder (
2,
5,
10). A study of 60 patients with skin picking disorder found a lifetime rate of co-occurring trichotillomania of 38.3% (
20), which is substantially higher than the rate of trichotillomania in the general population (0.6%–3.9%) (
20). Although few studies have compared these behaviors within and against each other, one comparative study of 33 individuals with skin picking disorder, 24 with trichotillomania, and 20 with co-occurring disorders found significant similarities across all groups (
2). Onset age, gender ratio, prevalence of both current and lifetime comorbid psychiatric disorders, and overall symptom severity were similar across all three groups (
2). Neurocognitive data, however, suggest that while there is overlap overall between skin picking disorder and trichotillomania, these are not manifestations of the same disorder. A direct comparison of skin picking disorder and trichotillomania (
25) demonstrated that while skin picking disorder was associated with significantly impaired stop-signal reaction times but intact cognitive flexibility relative to healthy comparison subjects, trichotillomania occupied an intermediate position in terms of stop-signal reaction times between comparison subjects and individuals with skin picking disorder.
Screening in Medical Settings
Many individuals with skin picking disorder begin picking at the onset of a dermatological condition such as acne (
17), but the picking continues even after the dermatological condition clears. Although the face is the most commonly reported site of picking, other areas, such as the hands, fingers, torso, arms, and legs, are also common targets (
2,
5,
6,
8,
15,
17,
18). In a study of 60 individuals with skin picking disorder, respondents reported picking an average of 4.5 sites (
11). Many individuals report having a primary body area for picking but may pick at other areas to allow the most significantly excoriated areas to heal (
2,
6). For most individuals with skin picking disorder, a variety of picking lesions can be seen, ranging from a few to hundreds (
18). Although most individuals pick at areas they can reach with their fingernails, many report using knives, tweezers, pins, and other objects to pick (
15,
18).
Picking may result in significant tissue damage and often leads to medical complications such as localized infections and septicemia (
2,
17,
18). Patients are often too ashamed to report areas that have become infected or where picking is particularly severe. A thorough physical examination is often needed to accurately assess the extent and severity of picking. Topical or oral antibiotics may be needed. The repetitive, excoriative nature of picking in severe cases may even warrant skin grafting (
2,
5) and has resulted in the development of an epidural abscess and paralysis (
26). In rare cases, the behavior can be life-threatening, as demonstrated by the case report of a 55-year old man whose picking on his back required multiple blood transfusions because of excessive blood loss (
27).