22.3 Psychodermatology, Delusional Infestation & Factitious Disorders

22.3 Psychodermatology, Delusional Infestation & Factitious Disorders

Psychodermatology sits at the interface of dermatology, psychiatry, and clinical psychology. Because the skin and the central nervous system share a common embryological origin in the ectoderm, neurocutaneous signaling pathways—mediated by neuropeptides (substance P, calcitonin gene-related peptide), neurotransmitters, and the hypothalamic-pituitary-adrenal (HPA) axis—closely link psychological stress to cutaneous inflammation.

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Classification of Psychodermatological Disorders

The European Society for Dermatology and Psychiatry (ESDaP) and international consensus classifications divide psychodermatological diseases into three distinct diagnostic categories:

1. Psychophysiological (Neuro-Immuno-Cutaneous) Disorders

• Definition: Genuine, biologically determined dermatological diseases that have an established pathophysiological basis but are demonstrably precipitated, aggravated, or sustained by psychological stress, anxiety, or emotional distress.
• Representative Disorders:
  • Psoriasis: Acute psychological distress triggers corticotropin-releasing hormone (CRH) release and cutaneous mast cell degranulation, precipitating severe inflammatory flares.
  • Atopic Dermatitis: Stress impairs stratum corneum barrier integrity, accelerates transepidermal water loss (TEWL), and amplifies pruritus via the itch-scratch cycle.
  • Alopecia Areata: Acute neurogenic inflammation disrupts hair follicle immune privilege.
  • Acne Vulgaris: Neuroendocrine stimulation upregulates sebocyte lipogenesis.
  • Others: Lichen planus, rosacea, seborrhoeic dermatitis, chronic spontaneous urticaria, and hyperhidrosis.
• Management: Standard dermatological pharmacotherapy combined with stress reduction modalities (mindfulness-based cognitive therapy, progressive muscle relaxation, biofeedback).

2. Primary Psychiatric Disorders with Cutaneous Manifestations

• Definition: Conditions where no underlying primary dermatological disease exists; the cutaneous lesions are entirely produced by the patient's own repetitive behaviors, compulsive impulses, or fixed, somatic delusional beliefs.
• Representative Disorders:
  • Delusional Infestation (Ekbom syndrome): Fixed delusion of parasitic infestation.
  • Morgellons Disease: Variant of delusional infestation involving reported cutaneous fibers.
  • Body Dysmorphic Disorder (BDD): Disabling preoccupation with imagined appearance flaws.
  • Excoriation (Skin-Picking) Disorder (Dermatotillomania): Compulsive skin excoriation.
  • Trichotillomania: Compulsive hair-pulling disorder.
  • Dermatitis Artefacta (Factitious Disorder): Self-inflicted skin lesions to adopt the sick role.
  • Delusions of Bromosis (Olfactory Reference Syndrome): Fixed false belief that one emits a foul, offensive body odor.
• Management: Psychopharmacology (atypical antipsychotics, SSRIs), habit-reversal training, and specialized psychiatric consultation.

3. Secondary Psychiatric Disorders

• Definition: Psychiatric complications—predominantly major depressive disorder, generalized anxiety disorder, social anxiety disorder (social phobia), adjustment disorders, and suicidal ideation—that develop as a direct psychological reaction to having a disfiguring, painful, pruritic, or socially stigmatizing skin disease.
• Representative Disorders:
  • Severe facial nodulocystic acne, extensive vitiligo, hidradenitis suppurativa (Hurley stage II/III), severe plaque psoriasis, alopecia totalis/universalis, and neurofibromatosis type 1.
• Management: Aggressive dermatological disease control alongside psychological counseling, peer support groups, and antidepressant pharmacotherapy when indicated.

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Delusional Infestation (Ekbom Syndrome)

Delusional Infestation (DI), historically known as delusional parasitosis or dermatozoic delusion, is the prototypical primary psychiatric disorder encountered in dermatological practice.

Clinical Manifestations and the "Specimen Sign"

• Core Psychopathology: A fixed, unshakeable false belief (delusion) that the skin, body, or internal organs are infested by living organisms (insects, mites, worms, bugs) or inanimate inanimate synthetic fibers/particles, despite the complete absence of clinical, microscopic, or entomological evidence.
• Demographic Profile: Most commonly affects middle-aged to elderly females (female-to-male ratio approximately 2.5:1; peak incidence >55–60 years); when presenting in younger adults (<40 years), males are equally represented, and illicit substance abuse must be actively ruled out.
• Cutaneous Findings: The patient's skin exhibits no primary dermatological lesions. The only observable signs are secondary mechanical damage inflicted by the patient attempting to extract or eradicate the imagined parasites: excoriations, deep erosions, punctate crusts, linear ulcers, and chemical burn dermatitis from toxic self-cleansing agents (bleach, kerosene, hydrogen peroxide, veterinary insecticides).
• The Pathognomonic "Specimen Sign" ("Matchbox Sign"): The patient presents to the clinic carrying small containers (matchboxes, zip-lock plastic bags, clear adhesive tape strips, ointment jars) containing lint, thread, scab fragments, dried keratin, and household dust, insisting they represent captured "parasites" or "larvae". Demonstrating that the contents are inanimate fibers under microscopic examination rarely shakes the patient's delusion.

Primary vs. Secondary Delusional Infestation

Clinicians must systematically differentiate between primary and secondary delusional infestation:

1. Primary Delusional Infestation:
   • Classified under DSM-5 as a Delusional Disorder, Somatic Type.
   • Represents an isolated, encapsulated delusion with a well-preserved personality, normal cognitive function, and absence of thought disorganization, bizarre behaviors, or auditory hallucinations.
2. Secondary Delusional Infestation:
   • The delusion arises secondary to an identifiable underlying medical, neurological, or substance-induced condition:
   • Medical / Endocrine / Metabolic Causes: Severe vitamin B12 or folate deficiency, iron deficiency anemia, hyperthyroidism or hypothyroidism, chronic renal failure (uremic pruritus), chronic hepatic failure, neurosyphilis, HIV/AIDS, multiple sclerosis, stroke, and early dementia.
   • Substance-Induced & Pharmacological Causes:
     • Illicit drugs: Cocaine ("cocaine bugs") and amphetamines/methamphetamine ("meth bugs" / "crank bugs"), which induce intense tactile hallucinations (formication) via massive central dopamine surges.
     • Prescription medications: Dopamine agonists used in Parkinson's disease (pramipexole, ropinirole, levodopa), ciprofloxacin, and abrupt corticosteroid withdrawal.

• Mandatory Diagnostic Workup: Every patient presenting with delusional infestation requires a thorough laboratory screening panel to exclude secondary medical causes:
  • Complete blood count (CBC) with differential
  • Comprehensive metabolic panel (creatinine, BUN, liver enzymes, electrolytes)
  • Thyroid-stimulating hormone (TSH) and free T4
  • Serum vitamin B12, serum and red blood cell folate, ferritin
  • Treponemal syphilis serology (treponemal EIA / TPPA) and HIV 1/2 antibody/antigen testing
  • Urine toxicology screen for cocaine and amphetamines

Therapeutic Communication: The ESDaP Consultation Protocol

The doctor-patient relationship is the single most critical factor in managing delusional infestation. Direct confrontation immediately ruptures rapport and drives the patient away.

Pharmacological Treatment: Modern Atypical Antipsychotics

• First-Line Pharmacotherapy: Second-generation (atypical) antipsychotics are the modern gold standard. They provide dopamine D2 receptor antagonism with lower rates of extrapyramidal symptoms than older agents. QTc prolongation, metabolic effects, and hyperprolactinaemia can still occur, so baseline ECG and metabolic checks are prudent:
  • Risperidone: Initiate at 0.5 mg to 1.0 mg once daily at bedtime; titrate gradually up to a maintenance dose of 1.0 to 2.0 mg daily (rarely up to 3.0 mg). Exhibits the largest published evidence base for delusional infestation.
  • Aripiprazole: Initiate at 2.0 mg to 5.0 mg once daily; titrate to 5.0 to 10.0 mg daily. Acts as a partial dopamine D2 agonist, with an excellent metabolic profile and minimal risk of hyperprolactinemia or sedation.
  • Olanzapine: 2.5 mg to 10 mg daily at bedtime; highly useful if the patient suffers from severe comorbid insomnia and agitation, but requires monitoring for weight gain and metabolic syndrome.
• The Historical Role of Pimozide:
  • Pimozide, a first-generation diphenylbutylpiperidine antipsychotic, was historically considered the treatment of choice because its intrinsic opioid receptor antagonist properties helped relieve peripheral pruritus.
  • Why Pimozide Is No Longer First Line: Pimozide carries a dangerous propensity for dose-dependent QTc interval prolongation, precipitating life-threatening ventricular arrhythmias (torsades de pointes), and a high incidence of extrapyramidal adverse effects (acute dystonia, parkinsonism, tardive dyskinesia). Baseline and serial electrocardiograms (ECGs) were mandatory. In modern European practice, pimozide is no longer first line.

Morgellons Disease: Clinical Context

• Definition: A distinctive somatic variant of delusional infestation wherein patients report that multicolored inanimate fibers, filaments, or crystals emerge from or are embedded within their skin, accompanied by severe formication.
• Scientific Investigation: A US Centers for Disease Control and Prevention (CDC) study published in 2012 examined skin samples and fibres from affected patients. The fibres were mostly cellulose, consistent with cotton or other textile fibres, often trapped in crusts; no infectious cause was found.
• Management: Identical to delusional infestation: avoid confrontation, rule out secondary systemic disease, build a therapeutic alliance, and initiate low-dose atypical antipsychotics.

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Body Dysmorphic Disorder (BDD)

Body Dysmorphic Disorder (dysmorphophobia) is characterized by an excessive, distressing preoccupation with perceived defects in physical appearance that are unnoticeable or appear slight to others.

Diagnostic Criteria & Clinical Presentation

• DSM-5 Criteria: Preoccupation with one or more perceived defects or flaws in physical appearance; performing repetitive behaviors (mirror checking, excessive grooming, skin picking, seeking reassurance) or mental acts (comparing appearance with others); causing clinically significant distress or functional impairment.
• Anatomical Preoccupations: The skin is the most frequent focus of concern (present in >70% to 80% of dermatology BDD patients), typically involving minimal or nonexistent facial pores, subtle blemishes, minor acne scars, wrinkles, oily skin, or imagined vascular flushing. Other common sites include the nose, hair (thinning), and genitalia.
• Prevalence in Aesthetic Practice: While BDD affects roughly 1% to 2% of the general population, its prevalence skyrockets to 10% to 15% among patients seeking care in cosmetic dermatology and plastic surgery settings.

Absolute Contraindication to Aesthetic Procedures

Key Clinical Rule: Cosmetic dermatological procedures, laser interventions, aesthetic injectables (dermal fillers, neurotoxins), and plastic surgery should generally be avoided in patients with Body Dysmorphic Disorder.

• Rationale: Studies show that the great majority of aesthetic procedures fail to improve BDD symptoms. The patient either remains intensely dissatisfied with the operated site, claims the procedure "deformed" or "mutilated" them, or instantly transfers their somatic obsession to another body part.
• Medicolegal & Personal Safety Perils: Dissatisfied BDD patients frequently initiate medical malpractice litigation, post defamatory public complaints, or make physical threats against the treating physician. BDD carries a tragically high lifetime suicide attempt rate (exceeding 20% to 25%), with completed suicide rates 45 times higher than the age-matched general population.
• Evidence-Based Treatment:
  • Psychiatric referral to an ESDaP-registered psychodermatologist or psychiatrist.
  • Cognitive Behavioral Therapy (CBT): Specifically tailored for BDD, incorporating exposure and response prevention (ERP) and perceptual mirror retraining.
  • Pharmacotherapy: High-dose Selective Serotonin Reuptake Inhibitors (SSRIs)—such as escitalopram (20 to 30 mg/day), fluoxetine (40 to 80 mg/day), or sertraline (150 to 200 mg/day). BDD typically requires higher SSRI dosages and longer treatment durations (12 to 16 weeks) than major depression.

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Excoriation Disorder & Trichotillomania

Excoriation (Skin-Picking) Disorder (Dermatotillomania)

• Core Features: Recurrent, compulsive picking, scratching, or digging into one's own skin, leading to noticeable tissue damage, despite repeated attempts to reduce or stop the behavior.
• Clinical Presentation: Polymorphous lesions in varying stages of healing—punctate erosions, linear excoriations, crusts, post-inflammatory hyperpigmented macules, and small, pitted, atrophic ("varioliform") scars. Lesions are situated strictly on easily reachable anatomical areas (face, extensor arms, upper chest, shoulders).
• Psychological Drivers: Picking is typically preceded by feelings of tension, anxiety, boredom, or tactile scanning for skin irregularities (e.g., small comedones or follicular bumps), and is followed by a temporary sense of relief or gratification.
• Treatment:
  • Habit-Reversal Training (HRT): Behavioral therapy focused on awareness training, competing response training (e.g., clenching fists or manipulating a stress ball whenever the urge arises), and stimulus control.
  • Pharmacotherapy: N-acetylcysteine (NAC) at doses of 1200 mg to 2400 mg daily has shown benefit over placebo in randomised trials in trichotillomania and skin picking, probably by modulating glutamatergic neurotransmission in the nucleus accumbens. High-dose SSRIs serve as an effective second-line therapy.

Trichotillomania (Hair-Pulling Disorder)

• Core Features: Recurrent pulling out of one's own hair, resulting in noticeable hair loss, despite repeated attempts to stop.
• Clinical Presentation: Asymmetric, irregularly shaped, bizarre, or geometric patches of non-scarring alopecia, predominantly involving the scalp (frontoparietal region), eyebrows, or eyelashes. Within the patch, hair density is reduced, but the area is never completely bald (unlike the smooth patches of alopecia areata).
• Trichoscopy / Dermoscopy Key Diagnostic Features:
  • Hairs broken at varying lengths: Pathognomonic hallmark representing irregular mechanical breakage.
  • Coiled (hook) hairs: Snapped hair shafts that coil back on themselves due to elastic recoil.
  • Flame hairs: Wavy, shredded proximal hair shafts produced by severe traction.
  • Tulip hairs: Short hair shafts with a dark, flower-like fractured distal tip.
  • Black dots: Severely fractured hairs level with the follicular ostia.
  • ABSENCE of exclamation mark hairs: Exclamation mark hairs (short broken hairs with a thin, hypopigmented proximal base and thick, dark distal tip) are the diagnostic hallmark of alopecia areata and are never seen in pure trichotillomania.
• Histopathology: Perifollicular hemorrhage, empty anagen hair follicles, follicular plugs with melanin granules (pigment casts), and catastrophic trichomalacia (distorted, fractured hair shafts).
• Systemic Complication: Trichophagia & The Rapunzel Syndrome:
  • A subset of patients (up to 20%) engage in trichophagia (swallowing the pulled hairs).
  • Indigestible human keratin accumulates in the stomach to form a massive hairball known as a trichobezoar.
  • In Rapunzel syndrome, the gastric trichobezoar develops a long "tail" of hair that extends through the pylorus into the duodenum and jejunum.
  • Complications: Severe abdominal pain, nausea, vomiting, early satiety, severe microcytic iron deficiency anemia, bowel obstruction, gastric ulceration, and life-threatening bowel perforation. Requires emergency surgical gastrotomy.

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Dermatitis Artefacta (Factitious Disorder)

Dermatitis artefacta represents the deliberate, conscious production of cutaneous lesions to satisfy an unconscious internal psychological need to adopt the "sick role".

Clinical Presentation and Morphological Hallmarks

• Lesion Morphology: The cutaneous lesions display an unmistakable artificial, geometric, unnatural configuration. They present as sharp-edged, linear, rectangular, triangular, or circular erosions, deep chemical burns, puncture wounds, or necrotic sloughs. Patterns never conform to any recognized dermatological disease.
• Anatomical Distribution: Lesions are strictly confined to anatomical sites readily accessible to the patient's dominant hand (face, neck, chest, anterior thighs, arms). The mid-upper back, which is inaccessible to self-injury, is conspicuously spared—a diagnostic sign termed the "butterfly sign".
• Patient Demeanor: "La Belle Indifférence": Patients typically recount the sudden, overnight emergence of severe, mutilating wounds with an eerie, smiling detachment and complete lack of appropriate emotional concern. The clinical history is "hollow"—the patient cannot describe how the lesion evolved, only that they "woke up and it was there."

Dermatitis Artefacta vs. Malingering

Key Distinction: The fundamental differentiator between dermatitis artefacta and malingering is the nature of the underlying motivation.

Clinical Management: The Occlusive Barrier Strategy

1. Avoid Confrontation: Directly accusing or exposing the patient results in immediate denial, hostility, flight from the clinic, and dangerous escalation of self-harm at another hospital.
2. Occlusive Dressings (The Protective Cast):
   • Apply rigid, tamper-evident occlusive dressings that mechanically prevent the patient from touching the skin: an Unna boot (zinc oxide impregnated bandage), a plaster cast, or a multi-layer adhesive dressing.
   • Clinician Framing: "This specialized medicated boot protects your fragile skin from environmental toxins and allows healthy healing." Under occlusion, factitious ulcers heal rapidly within 10 to 14 days, confirming the diagnosis.
3. Psychiatric Liaison: Introduce psychological or psychiatric care gradually once a solid therapeutic alliance is established.