# Psychodermatology: Skin and the Mind

## Introduction

Psychodermatology is the interface between psychiatry and dermatology, addressing conditions where psychological factors play a significant role in skin disease, and skin disease causes substantial psychological morbidity. The skin and the nervous system share ectodermal embryologic origin, and the brain-skin axis involves complex neuroimmune and neuroendocrine pathways. Dermatologists encounter psychodermatologic conditions frequently, and recognition enables appropriate treatment that addresses both the cutaneous and psychiatric dimensions.

## Classification of Psychodermatologic Disorders

### Category I: Primary Psychiatric Disorders with Cutaneous Manifestations

In this category, skin lesions are entirely self-induced and there is no underlying primary dermatologic disease. The patient creates or fabricates cutaneous findings as a direct consequence of psychiatric illness. Examples include dermatitis artefacta, trichotillomania, delusions of parasitosis, and neurotic excoriations.

### Category II: Primary Dermatologic Disorders with Psychological Sequelae

These are real skin diseases that cause significant secondary psychiatric comorbidity such as depression, anxiety, and social isolation. Conditions like psoriasis, acne, vitiligo, alopecia areata, atopic dermatitis, and hidradenitis suppurativa fall into this category. Up to 30% of dermatology patients carry significant psychological comorbidity.

### Category III: Psychophysiologic Disorders

In these conditions, a primary skin disease is exacerbated by psychological stress. Stress activates the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system, releasing cortisol, catecholamines, neuropeptides such as substance P and CGRP, and mast cell mediators that modulate inflammation. Examples include psoriasis with stress-triggered flares, atopic dermatitis with its itch-scratch cycle, urticaria, rosacea, and hyperhidrosis.

## Primary Psychiatric Disorders

### Delusions of Parasitosis (Delusional Infestation)

Delusions of parasitosis involves a fixed, false belief that the skin is infested with parasites, insects, fibers, or other organisms. Patients present with excoriations, erosions, and ulcers from digging, picking, and scrubbing at their skin. The classic "matchbox sign" or specimen sign is pathognomonic: patients bring collections of skin debris, lint, scabs, or fibers as "proof" of infestation. There is no primary skin lesion, and all findings are secondary to self-manipulation.

This condition may occur as a primary delusion, also called monosymptomatic hypochondriacal psychosis, or it may be secondary to medical conditions including drug use (cocaine, methamphetamine), B12 or folate deficiency, thyroid disease, hepatic or renal failure, or dementia. Folie a deux, a shared delusion with a close contact such as a partner or family member, occurs in approximately 5 to 15% of cases.

#### Workup

Evaluation requires a thorough skin examination and appropriate testing to definitively exclude true infestation, including scabies preparation, skin scraping, and dermatoscopy. Laboratory studies should include CBC, CMP, TSH, B12, folate, urinalysis with drug screen, HIV, and hepatitis serologies. Neuroimaging should be considered in elderly patients with new-onset delusions.

#### Treatment

Building rapport is essential. The clinician should never directly contradict the delusion but must also avoid reinforcing it, instead acknowledging the patient's suffering. Antipsychotics are the mainstay of treatment. Pimozide is the traditional first-line agent but requires ECG monitoring for QTc prolongation. Risperidone offers a better side-effect profile at doses of 0.5 to 2 mg per day and is increasingly preferred. Olanzapine and aripiprazole are alternatives. The response rate to antipsychotics is approximately 50 to 75% with significant improvement. Long-term treatment is often necessary, as relapse is common with discontinuation.

<image>Clinical photograph of a patient with delusions of parasitosis showing self-inflicted excoriations and ulcerations on accessible body areas (arms, face, legs) alongside an image of the specimen sign (matchbox sign) with collected skin debris brought by the patient as evidence of infestation</image>

### Dermatitis Artefacta (Factitial Dermatitis)

Dermatitis artefacta is characterized by self-inflicted skin lesions that the patient denies creating. It is distinguished from neurotic excoriations, where the patient acknowledges picking, and from malingering, where there is an external incentive. Lesions are typically geometric, bizarre-shaped, and sharply demarcated, found exclusively on accessible areas. Common methods include burning with cigarettes or chemicals, cutting, application of caustic agents, injection of foreign material, and tourniquet application.

The "hollow history" is characteristic: the patient cannot explain how the lesions appeared and may seem oddly indifferent, a phenomenon termed la belle indifference. The typical demographic is young women with underlying personality disorders or dissociative disorders.

#### Management

Accusatory confrontation must be avoided, as it ruptures the therapeutic relationship. A gentle, non-judgmental approach is preferred, such as stating "Your skin is being damaged; let's work together to help it heal." Occlusive dressings prevent access to the skin and allow lesions to heal underneath. Psychiatric referral for underlying psychopathology, often personality disorders or trauma history, is essential. The prognosis is variable, with many patients following a chronic and relapsing course.

### Trichotillomania

Trichotillomania involves compulsive hair pulling resulting in patchy, irregular alopecia. It is now classified as an obsessive-compulsive related disorder in the DSM-5. While it typically involves the scalp, it can also affect the eyebrows, eyelashes, and pubic hair. On examination, irregular patches of alopecia with broken hairs of varying lengths are seen, without scarring unless the condition is chronic, and the hair pull test is negative. Trichoscopy reveals black dots, coiled hairs, the V-sign (two broken hairs emerging from one follicle), flame hairs, and tulip hairs. If biopsy is performed when the diagnosis is unclear, it shows trichomalacia (distorted hair shafts in the follicular canal), pigment casts, and catagen or telogen hairs without inflammation.

#### Treatment

Habit reversal training is the first-line behavioral therapy, combining awareness training with competing response training. N-acetylcysteine at 1,200 to 2,400 mg per day is a glutamate modulator with randomized controlled trial evidence for efficacy. SSRIs are helpful for comorbid anxiety and depression but have limited efficacy for hair pulling itself. Clomipramine, a tricyclic antidepressant, has some evidence of superiority over SSRIs for trichotillomania specifically.

### Neurotic Excoriations (Excoriation Disorder)

Neurotic excoriations, also called skin-picking disorder or dermatillomania, involves repetitive skin picking. Unlike dermatitis artefacta, the patient acknowledges the behavior but cannot stop despite the desire to do so. It is classified as an OCD-related disorder in the DSM-5. Lesions consist of excoriations, erosions, and scars on accessible areas such as the face, arms, and upper back. Picking is often triggered by perceived skin imperfections such as acne or insect bites that are then excessively manipulated.

#### Treatment

Habit reversal training is the most effective behavioral intervention. SSRIs such as fluoxetine and sertraline are the first-line pharmacotherapy. N-acetylcysteine has growing evidence from randomized controlled trials. Wound care to prevent secondary infection is important, and topical retinoids may be useful when picking is triggered by acne.

<image>Diagnostic comparison chart showing key features distinguishing trichotillomania (irregular alopecia patches with broken hairs of varying lengths, no inflammation), alopecia areata (smooth, round patches with exclamation point hairs), and dermatitis artefacta (bizarre-shaped lesions with sharp geometric borders on accessible areas)</image>

| Condition | Category | Key Features | First-Line Treatment |
|-----------|----------|--------------|---------------------|
| Delusions of parasitosis | Primary psychiatric | Fixed belief of infestation; specimen sign; self-inflicted excoriations | Antipsychotics (risperidone 0.5–2 mg/day) |
| Dermatitis artefacta | Primary psychiatric | Self-inflicted bizarre/geometric lesions; hollow history; denial | Non-confrontational approach; occlusive dressings; psychiatric referral |
| Trichotillomania | Primary psychiatric (OCD-related) | Irregular alopecia; broken hairs of varying lengths; no scarring | Habit reversal training; N-acetylcysteine 1200–2400 mg/day |
| Neurotic excoriations | Primary psychiatric (OCD-related) | Acknowledged repetitive picking; excoriations on accessible areas | Habit reversal training; SSRIs; N-acetylcysteine |
| Psychophysiologic disorders | Stress-exacerbated | Real dermatosis worsened by stress (psoriasis, AD, urticaria) | Treat underlying dermatosis + stress management |

## Psychological Impact of Skin Disease

### Burden of Skin Disease

Dermatologic conditions rank fourth in global disability burden according to the Global Burden of Disease study. The Dermatology Life Quality Index (DLQI) is a validated ten-question tool measuring impact on daily life, and a score greater than 10 indicates severe impact. Conditions with the highest psychological impact include psoriasis, hidradenitis suppurativa, acne in adolescents, vitiligo, alopecia areata, and chronic urticaria.

### Specific Associations

Psoriasis carries a depression prevalence of approximately 25%, with suicidal ideation in 5 to 10%, along with social stigma and alcohol use disorder. Acne is associated with depression, anxiety, and suicidal ideation, and while the isotretinoin controversy has received much attention, evidence suggests that acne itself drives depression more than the medication. Vitiligo is associated with depression, social anxiety, and stigmatization, particularly in cultures where depigmentation carries social consequences. Hidradenitis suppurativa produces the highest DLQI scores of any dermatologic condition, as pain, odor, and disfigurement drive significant psychological morbidity.

### Screening for Psychiatric Comorbidity

The PHQ-2 and PHQ-9 (Patient Health Questionnaire) are useful for depression screening, while the GAD-7 (Generalized Anxiety Disorder scale) assesses anxiety. Direct inquiry about suicidal ideation should be made in high-risk patients, particularly those with severe acne, psoriasis, or chronic pain conditions.

## Psychopharmacology for the Dermatologist

### SSRIs

SSRIs are first-line agents for depression, anxiety, and OCD-related conditions such as excoriation disorder. Common choices include fluoxetine, sertraline, and escitalopram. Side effects include gastrointestinal upset, sexual dysfunction, and initial anxiety.

### Antipsychotics

Antipsychotics are used for delusional parasitosis and severe psychodermatologic conditions. Risperidone at 0.5 to 2 mg per day is preferred for its tolerability. Pimozide at 1 to 4 mg per day is the traditional choice but requires ECG monitoring for QTc prolongation and attention to CYP2D6 interactions. Olanzapine at 2.5 to 10 mg per day is an alternative, though it carries metabolic side effects including weight gain and hyperglycemia.

### Anxiolytics

Hydroxyzine serves as both an antihistamine and an anxiolytic, making it particularly useful for pruritus with an anxiety component. Gabapentin and pregabalin are helpful for neuropathic pruritus with anxiety. Benzodiazepines should be avoided for chronic use and have a limited role in psychodermatology.

## Clinical Pearls

The specimen or matchbox sign, in which patients bring collected "evidence" of infestation, is highly suggestive of delusions of parasitosis, but true infestation must always be excluded first. Patients with dermatitis artefacta should never be directly confronted; instead, the clinician should build trust, provide wound care, and gently facilitate psychiatric referral. N-acetylcysteine has growing randomized controlled trial evidence for trichotillomania and excoriation disorder and represents a well-tolerated treatment option. Clinicians should screen for depression and suicidal ideation in patients with severe psoriasis, acne, and hidradenitis suppurativa. Stress exacerbates psoriasis, atopic dermatitis, and urticaria through measurable neuroimmune pathways, and addressing psychological well-being is an integral part of comprehensive dermatologic care.

## References

1. Jafferany M, Franca K. Psychodermatology: basics concepts. *Acta Derm Venereol*. 2016;96(217):35-37.
2. Bewley A, Affleck A, Bundy C, et al. Psychodermatology in clinical practice. *Br J Dermatol*. 2013;168(6):1156-1159.
3. Grant JE, Chamberlain SR. Trichotillomania. *Am J Psychiatry*. 2016;173(9):868-874.
4. Lepping P, Freudenmann RW. Delusional parasitosis: a new pathway for diagnosis and treatment. *Clin Exp Dermatol*. 2008;33(2):113-117.