Introduction

Skin and neural tissue are both of ectodermal origin. Skin and brain influence in prenatal development in a bidirectional pattern. In post-natal life, environmental factors modify the skin-brain axis [1, 2]. One example of disturbed communication between these two tissues will be discussed: Self-inflicted dermatoses (SID) represent a heterogenous group of symptoms and diseases. Their prevalence has been estimated to be 0.9% what is probably underestimated [3].

Several classifications of SID can be found in the literature. For dermatologists the classification suggested by the European Society for Dermatology and Psychiatry (ESDaP) may be helpful [4]. The classification excludes self-mutilations since these are caused by primary psychiatric disorders including schizophrenia or mental retardation, obsessive compulsive disorders, suicide attempts and delusional disorders. These are also known as factitious disorders. Non-pathological self-inflicted skin modifications such as tattoos, piercings, esthetic procedures will not be discussed in the present review. Table I provides an overview on pathologic SID according to ESDaP.

The major difference between compulsive and impulsive disorders is that the formers are repetitive, done several times a day.

SID with hidden or denied underlying behavior

Malingering describes the behavior to produce symptoms, often aggravation of a pre-existent skin disease, due to social incentives. An example are self-inflicted wounds in a soldier to avoid combat, others are meant to gain a financial advantage.

Factitious disorders are lacking external incentives, although stress may be followed by factitious skin lesions. However, the primary driver of the disease is endogenous, often unconscious and a possible strategy to cope with severe psychological problems (Fig. 1 a-c). An important differential diagnosis is the trophic trigeminal syndrome with paresthesia. Here, self-inflicted lesion including ulcerations can be observed due to the missing pain sensation while picking or scratching [5].

Fig. 1: Self-inflicted dermatoses.
a–c: Factitious dermatosis with various degrees of ulcerations of facial skin. d+e: Skin picking, e: has some pathomimicry to pruriginous eczema. f: Morgellons disease with pathomimicry to tick bite.

Pathomimicry refers to the resemblance of self-inflicted lesions with naturally occurring skin disorders [6] (Fig. 1d). Münchhausen syndrome is characterized by a triad of symptoms such as (i) factitious symptoms; (ii) hospital or doctor shopping; and (iii) pseudologia phantastica [7]. Münchhausen syndrome by proxy describes the situation that a caregiver fabricated illness. This rare subtype raises ethical concerns to protect the child during probable critical conflicts between health professionals and the parents [8].

Gardner-Diamond syndrome or psychogenic purpura had been initially classified as an autoimmune disorder but is now classified as factitious. Nevertheless, autoimmune disorders should be excluded before confirming the diagnosis. Intradermal injection of autologous washes erythrocytes has been used for diagnostics. Twenty-four hours after injection painful ecchymosis will develop in most but not all patients [9].

SID without hidden and denied underlying behavior

Compulsive skin picking and related syndromes are listed in table II (Fig. 1e-f). Acne excoriée, trichotillomania, and onychophagia are more common. The first usually starts in adolescence with a female predominance. There is no relation between the severity of acne and the severity of skin picking. Acne is not the driver of this SID [10]. Trichotillomania also often begins in childhood but may also present in adult patients with a prevalence of up about 3% in general population. It can occur during day or even at nighttime during sleep. The disease may be associated with trichophagia and result in rare cases in Rapunzel syndrome where a tail of the trichobezoar extends into the intestines with a risk of intestinal obstruction [11]. Onychophagia of some kind can be observed in up to 45% of adolescents. It is often associated with stressful events. There are patients without an underlying behavioral disorder but poor coping with stressors [12].

Morgellons syndrome shows uncharacteristic cutaneous symptoms of scratching and picking, but the patients usually present material of filaments or fibers in small bags or boxes knowing as the matchbox sign. There is overlap to delusional parasitosis [14].

Diagnosis of SID

The diagnosis of SID is complex. In dermatologic practice a suspicion of SID depends upon presentation of clinical symptoms, distribution, medical history of the patients and sometimes also their family. The lesions are on easily accessible body parts, the shape may be irregular, the distribution does often not follow the pattern seen in natural dermatoses. In one study 40% of patients had multiple lesions [15]. There are no specific laboratory tests and not specific histopathologic findings. It is important to seek psychological/ psychiatric support for diagnosis.

Treatment

The real challenge of SID is their treatment. The role of dermatologists is auxiliary at its best. Topical treatment of wounds and prevention of soft tissue infections play a major role. N-acetyl-cystein may show promising effects in adolescent and adult patients with trichotillomania [16].

Cognitive behavioral therapy has been used as an effective treatment approach. It aims to improve coping, correct believes and behavior that maintain the stress. Several tools of cognitive behavioral therapy have been developed [17]. Medical drug therapy can be indicated but long-term adverse events and benefits for the patient need to be carefully considered and weigh up. Most SID will not be cured by drug therapy alone. In some patients, however, psychotropic medications may ameliorate symptoms. Fluoxetine or citalopram have been shown to improve symptoms of excoriation in factitious dermatitis. Depression, anxiety, or psychoses need to be treated as co-morbidities [18]. A tight collaboration of dermatologists, psychologists, psychiatrics, and psychotherapists seems to provide best outcome.

Conclusions

SID are not uncommon in dermatology, but their prevalence is obviously underestimated. Diagnosis is dependent on medical history, clinical presentation, and exclusion of “natural” dermatoses by histology and laboratory investigation. The treatment needs an interdisciplinary approach. The dermatologist is often the first in patient contact. Therefore, dermatologists should be able to recognize SID and to guide the patient in the interdisciplinary approach. Despite a better understanding of the psychology treatment far behind. The diseases often run a chronic course. Some disorders during childhood and adolescence, however, may disappear [19, 20].