Are You Confident of the Diagnosis?

A delusion is a false belief that is not consistent with the cultural standards or educational level of the individual, and that is unshakable in face of all evidence to the contrary. The patients whom we see in dermatology have “systematized” delusions. These, in contrast to “bizarre” delusions, are false but completely unshakable beliefs that have an inner consistency and are congruent with the life-style of the patient. The patient functions adequately in other aspects of life, and for this reason, hallucinations, if present, are consistent with the ideational content of the false belief. Bizarre delusions, by contrast, occur in psychotic individuals who have schizophrenia or bi-polar disorder, and whose life-style is chaotic, and relationships dysfunctional.

In dermatology we see a broad spectrum or delusional beliefs. Formerly the complaints were most commonly of infestation with known or unknown parasites. Recently, we have seen a wider variety of beliefs. These primarily constitute “Morgellons Disease”, in which symptoms are attributed to some unknown type of natural or synthetic fiber, or some as yet unknown but very powerful bacterium under, within or extruded from the skin. A third form of delusion is the belief that some aspect of the individual’s appearance is deformed or ugly, or that some bodily function is pathologically abnormal. These latter beliefs form the delusional end of the body dysmorphic spectrum. They will be addressed separately.

  • What you should be alert for in the history

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The history and clinical presentation of delusions of infestation are diagnostic. The patient is anxious, loquacious and repetitive. The symptoms appear to arise as follows: an altered sensation in the skin is usually first experienced focally. It extends gradually to become regional or generalized. The sensation may be itching, stinging, biting, burning, crawling, etc., and the patient will usually have had other consultations and many tests that have yielded neither cause nor relief, before reaching the dermatologist. The patient has often felt “brushed off”, or considered “crazy”. The onset may have been recent, or reportedly as long as 35 years previously. “Not knowing” the cause of the dysesthesia has made the patient very anxious, and the anxiety in turn, it seems, generates the false belief.

The ideational content of the belief is explained by the nature of the sensation and the life-circumstances at the time of onset. The belief is confirmed by the measures taken to seek relief. Doctor-shopping, lack of sleep, cleansing rituals, vast expenditure on unconfirmed “cures”, destruction of clothing and furniture, and isolation from family and friends are all part of the picture – one patient had burned a fur coat, said to be worth $10,000.

  • Characteristic findings on physical examination

The anxiety is immediately evident. The patient is frustrated and angry, feeling that physicians are either unfeeling or incompetent.

Physical examination is consistent with the content of the belief. The large plastic bags, boxes or adhesive tape, holding “specimens” submitted (rather than the small “match-boxes” of yore) are diagnostic. These represent skin debris, wool or cotton fibers, dust, and small environmental insects, etc.

Depending on the duration, the lesions consist of open or crusted excoriations, small circumscribed ulcers where perceived invaders have been “dug” out with needle, tweezers or knife-point, deep ulcers, scars or prurigo nodules (Figure 1), The areas on which the lesions occur help to trigger the specific delusional belief – lesions on the dorsal hands and the distal forearms may suggest scabies, the lower legs garden pests. Hotel rooms, borrowed furniture or clothing, also are often mentioned. As the lesions become more generalized, inaccessible areas such as the “butterfly” in the mid-scapular region will be spared. Mucous surfaces, however, are not spared, and the crawling of creatures out of every orifice may be described.

Figure 1.

Typical excoriations that one may see in patient with delusions of “bugs” coming from the skin.

  • Expected results of diagnostic studies

Work-up should include tests to rule out other causes of dysesthesia. These include bacterial and fungal cultures, and skin scrapings for possible scabies, complete blood count, metabolic profile, tests of hepatic and renal function, viral antibodies for hepatitis A,B, and C, antibodies to the human immunodeficiency virus, antinuclear antibodies, thyroid function, serum iron and iron-binding capacity and Vitamin B12. A screen for recreational drugs should also be done if the history or clinical picture suggests it is indicated, but in the vast number of cases these will be normal.

Lesional biopsy reveals the changes caused by rubbing, scratching, or picking, while the submitted specimens consist only of cutaneous debris, crusts, fluffs, fibers and perhaps small benign environmental insects. Examination by an entomologist reveals no parasitic organisms.

Who is at Risk for This Disease?

  • Epidemiology

Because the ideational content is determined by individual life-circumstances, patients may present first, either to the dermatologist, the primary physician, the psychiatrist, or the entomologist. Because of this fracturing of information, there are few studies to determine the incidence of cutaneous delusions, but the rapid spread of information through the Internet may account for an apparent significant increase in the incidence to well beyond the 0.02% suggested in the literature.

The sex ratio reportedly is F : M, 1 : 1 under 50 years of age, and 2 – 3 : 1 over 50. At particular risk are elderly women who live alone and have little social contact.

What is the Cause of the Disease?

  • Etiology

Formerly called a “monosymptomatic hypchondriacal psychosis”, it is now clear that the condition is NOT monosymptomatic and that patients may have a major depressive disorder, bipolar disorder, dementia or one of the personality disorders, such as avoidant, paranoid or schizoid. Similarly, patients with systemic disorders that may cause itching, such as severe anemia or lymphoma, hepatic or renal disease, and particularly patients on dialysis may develop the syndrome. It may also be a paramalignant phenomenon, or a consequence of prescribed opioids, or recreational drug use.

A similar cutaneous clinical picture, but without the delusional belief, may be seen in patients with neurotic excoriations, in the pruritic inflammatory dermatoses, and in the systemic disorders noted above.

  • Pathophysiology

Our understanding of the co-existent pathophysiology of the cutaneous dysesthesia itself is steadily unfolding, but is beyond the scope of this chapter.

Systemic Implications and Complications

The patient is not psychotic in the usual sense of the word, since he or she functions adequately in other areas of life. Frequent comorbidities are major depressive disorder, bipolar disorder, one of the personality disorders, dementia, fibromyalgia, chronic fatigue syndrome, chronic pain syndromes, irritable bowel syndrome and others of the somatising disorders. Comorbid physical conditions often are already under treatment at the time of referral, and should be looked for in the history.

Cutaneous delusions consume vast amounts of medical resources due to failure to diagnose, frequent visits to specialists in different fields, numerous and oft-repeated tests and prescription of ineffective medication.

As a result of manipulation and cutaneous ulcerations, secondary bacterial infection is not uncommon and may lead to abscesses and cellulitis. Scarring may be prominent.

The delusional belief is understood to be a defense against the patient’s recognition that he/she has psychological issues and, for this reason patients strongly resist psychiatric referral, fearing that they would again be thought “crazy”. Non-psychiatric physicians may not be comfortable with prescribing psychotropic drugs, and thus appropriate treatment may be denied the patient. Depression may be severe, and indeed, patients do become suicidal, and indeed, suicides do occur.

Other family members and close associates may develop similar symptoms in a folie a deux, reportedly this occurs in 12% of cases, but clinical experience would suggest this to be a high estimate. Suicides do occur.

Treatment Options

The development of a therapeutic doctor-patient relationship.

Intensive topical treatment.

Systemic medication:

  • – Antipsychotics

  • – Antidepressants

  • – Anticonvulsants

  • – Antihistamines

Optimal Therapeutic Approach for this Disease

The Doctor-Patient Relationship

A therapeutic doctor-patient relationship is crucial. This must be empathic and must generate trust in the patient. Trust is essential if the patient is to be willing to accept appropriate medication.

It is important to see the patient frequently at first. This will demonstrate interest and establish trust. It is important to reassure the patient that indeed something is going on in the skin, not “all in the head”. Empathize with the various levels of distress that the patient reports. Explain the symptoms in ways that are both honest and acceptable to the patient; e.g., in terms of neurochemical release in the skin in response to stress, etc. Introduce medication in a way that will allow the patient to feel justified in taking it; e.g., because it helps to inactivate the neurochemicals.

One may point out to the patient how much the symptoms are impacting the patient’s life in negative ways, and how medication may help the patient better to deal with that. Throughout the relationship, try to reach a level at which psychiatric referral can be obtained. Try also to find a way to introduce the concept such that it may feel like a joint decision, not an idea imposed on the patient by the physician. The ideal is to have a clinic in which a psychiatrist can consult with the dermatologist. If this is not available, until one is able to make a psychiatric referral it is very helpful to have a psychiatrist with whom one can consult, even by telephone.

Topical Medications:

Because the skin is over-valued, topical treatment is very important. Tar baths or compresses are helpful. They are anti-inflammatory, and also may be new to the patient. Alternatively, Clorox baths may seem more logical to the patient. Emollients help to maintain barrier function. Antipruritic lotions containing pramoxine, menthol 0.5% or phenol 0.5% have an immediate antipruritic action, but do not speed healing. Antibiotic ointments (e.g., triple antibiotic, or mupuricin), should be applied to open areas, and a potent corticosteroid ointment (e.g., betamethasone ointment 0.05%) may be applied to any itching area, whether open or not, to reduce itching.

As dysesthesia becomes less, so may delusional thinking and tissue damage. Provided that topical and oral antibiotics are prescribed as indicated, there is little risk of spreading infection with the topical steroid.

Prurigo nodules may be injected with a triamcinolone suspension containing 10-40 mg/ml at monthly intervals as needed, depending on the degree of thickening. A topical retinoid (eg, tretinoin 0.01% cream, gel or lotion may be applied to decrease scarring.)

Oral Medications:

There are no medications approved by the FDA specifically for treating this disorder. One must be frank about this with the patient, and openly discuss what are the approved uses and the possible side effects of the drugs prescribed. Oral antibiotics should be given as needed, based on the clinical picture, cultures and biopsies.


The atypical antipsychotics are the drugs of choice. Should one drug in this class not prove effective, then another in the same class may be tried. Much lower doses are effective than are usually prescribed in psychiatry. The sensory symptoms and the comorbid psychiatric symptoms, such as anxiety and depression, can be expected to resolve in parallel with the delusional ideation.

Pimozide has been prescribed effectively for the past three decades without reports of significant side effects in the dermatology literature. In addition to action on the dopamine pathways, pimozide blocks the mu opioid receptors, making it a potent antipruritic. Pimozide is given as a single dose in the morning. The usual effective dose is .0 – 5.0 mg, starting with 1/2 mg. and titrating up by 1/2 mg. every 3-5 days to avoid possible side effects. Benefit can usually be noted within 2 weeks, and slow steady improvement can be anticipated thereafter.

There are few reliable controlled trials for treatment of cutaneous delusions, but response rates of up to 90% are reported. Parkinsonian side-effects and akathisia can be prevented by prescribing benztropine myselate 1.0 mg 2-3 times daily, or diphenhydramine 25 mg up to 4 times daily. Lengthening of the Q-T interval may occur, but reportedly cardiac side effects do not occur with a dose less than 10 mgs daily, and an EKG is recommended only with that dose and above.

Clearly care must be taken if the patient is taking other drugs that affect the Q-T interval, or if there is a history of heart disease. Tardive dyskinesia is also a reported side effect, but to date there are no credible reports of that complication in the dermatology literature.

Aripiprazole and risperidone are other drugs reported effective. Reportedly their side effect profiles are not too dissimilar from that of pimozide. Aripirazole 5.0 mg may be increased to 10mg in 1 week, while a daily dose of risperidone 0.5-1.0mg may be raised by 0.5mg per day, each week, to a total of 4.0mg daily, as needed. Olanzepine is not recommended because of the possibility of weight gain and development of the metabolic syndrome.


Rarely does one need a drug other than one of the atypical antipsychotics for anxiety, but should anxiety be severe, an anxiolytic may be prescribed for immediate impact before the antipsychotic takes effect. The benzodiazepines are potentially habit-forming, but act immediately. Alprazolam 0.25 mgs – 1.0 mg up to four times daily, as needed, or clonazepam 1.0-2.0 mgs. at bed time could be prescribed.

However, the antidepressants also have antianxiety action, and the antianxiety medication can usually be weaned, once the antidepressant has taken effect.


The Serotonin Reuptake Inhibitor antidepressants (S.S.R.I’s) are by and large effective, and easy to use. Sertraline is usually well-tolerated, and, in addition to its antidepressant action it is an effective anxiolytic, and has some antipruritic action. Sertraline 50.0 mg once daily in the morning may be raised by 50.0 mg/day every 3-5 days, to a total of 200.0 mg daily, given as a single dose.

Amitriptyline, a tricyclic antidepressant, may also be prescribed for anxiety and as an antipruritic agent. Usually a dose of 75.0 mg once daily at bedtime is prescribed for this purpose.


Gabapentin and pregabalin both have some antipruritic action, and may be prescribed if control of dysesthesia proves difficult. Gabapentin 300.0 mg may be prescribed once daily at bed-time, and increased by 300.0 mg each week to a total of 300.0 mg 3 times daily. The dose of pregabalin is 50.0 mg at bedtime, increasing in the same manner to a total of 50.0 mg 3 times daily.


Because histamine is not the major mediator of dysesthesia in these disorders, antihistamines have not been found to be effective.

Body Dysmorphic Delusions

Body dysmorphic disorder (BDD) refers to a condition in which the individual has a concern that he or she is ugly or deformed in some way. There is a broad spectrum of severity in this condition, from relatively benign everyday displeasure with a physical feature through severe obsessional concerns and destructive compulsive behaviors, to a frankly delusional state in which a perfectly normal feature is misperceived as ugly or deformed. The delusional form of BDD is a systematized delusion in a patient who functions adequately in other aspects of life.

The patient with BDD spends long hours each day studying the feature that is of concern, seeking reassurance from family and friends, and checking his or her appearance in any reflective surface that may be encountered. Social isolation is common, and the symptom interferes in every aspect of the patient’s life. Shame and embarrassment are crippling, relationships may be destroyed and work impossible. As with delusions of parasitosis and Morgellons disease, many doctors are consulted, but in this case surgical procedures are requested in order to remove or reconstruct the perceived ugly or deformed feature.


The incidence of BDD is 2% in the general population, and 6-9% in the dermatologic population. It is not clear what proportion of these patients are frankly delusional, but in one series, 50% of patients seeking aesthetic surgery had a delusional belief about some feature of his or her appearance.

The onset is usually in adolescence, though shame may delay consultation for 10 years or more. The gender incidence is essentially equal, though women are more likely to seek treatment, and for them concerns are primarily about the nose, face or breasts, while for men, the nose, hair loss, muscle definition, or the genitalia are the common foci.

Other common presentations of BDD are the olfactory reference syndrome (a hallucination), in which the patient believes him or herself to be exuding an offensive odor, and the red-scrotum syndrome, in which the patient complains of pain in the scrotal skin, or perceives the skin to be abnormally reddened.

Systemic Implications and Complications

It is important for the physician not to allow him or herself to be manipulated into agreeing to perform any surgical procedure in the patient with dysmorphic delusions. Because the focus of concern is not seen realistically, no procedure can achieve a result that will satisfy the patient, and patients sometimes will go through one after another plastic surgical procedure, at great expense, and with no improvement, in the eyes of the patient. Rather than making a completely normal feature more beautiful, there may, in the end, be frank deformity. Patients may become more deeply depressed and angry. Sometimes surgeons are attacked or even murdered, and suicides do occur.


The treatment is psychiatric, and no dermatologic treatment is likely to have a positive impact. The doctor-patient relationship again is important; and trust is essential if a meaningful referral is to be made.

Rather than the antipsychotics, the selective serotinin reuptake inhibitos (SSRIs) are most effective, even in the delusional manifestation of BDD. Doses at the higher end of the dosing schedule are usually needed. The addition of an antipsychotic to the SSRI regimen may be helpful in resistant cases.

The other effective treatment is cognitive -behavioral psychotherapy, but as with other cutaneous delusions, psychiatric referral is not easy, and long-term treatment is usually necessary.

Patient Management

If a psychodermatology clinic is not available, it is very helpful to have a psychiatrist with whom one can consult about treatment and progress. Most important for effective management is maintenance of a trusting relationship. It is important to continue to see the patient frequently until all symptoms are resolved.

Since use of psychotropic drugs for patients with DOP is off-label, and because these drugs have possible side effects, it is important to discuss these issues with the patient. This discussion must be undertaken cautiously, with tact and reassurance; otherwise, the patient will refuse the only medication that can help. As the doses that are effective for our patients are small, side effects are not excessive, and usually will improve over time.

Be alert to the patient’s mood. Remember that depression is common and that suicides do occur. Once the antipsychotic has started to take effect, mood usually will improve along with the other symptoms.

Once the DOP patient is free of symptoms for a period of 2 or 3 months, the medication can very gradually be tapered over a period of months. Should there be a recurrence of symptoms during that time, the dose should be raised again, and a response can again be expected. Should this not be the case, another psychotropic drug can be tried.

It is important to instruct the patient not to discontinue the medication abruptly or unilaterally, because the rapid and unexpected recurrence of symptoms may cause trust to be broken, and the patient to resume doctor-shopping.

Unusual Clinical Scenarios to Consider in Patient Management

Because of the personality configuration of patients with DOP, loyalty may not be prominent, and if for any reason symptoms should persist or recur the physician should not feel guilty or ineffective if the patient resumes doctor-shopping.

The reported prognosis for response to therapy in DOP varies widely, but 75% – 90% of cases experience a partial or complete response, with remissions of variable length. In one series long-term remission was reported in 50% of cases.

The response of BD delusions is usually good, but long-term treatment is necessary. Should a recurrence not respond to the first drug chosen, in either form of cutaneous delusions, a second drug in the same class can be prescribed. Should depression recur, psychiatric referral would be ideal, but if circumstances make that impossible, an antidepressant can be added to the regimen.

Folie à deux, or folie partagée, refers to a condition in which one or more others in addition to the target case are believed to be infested. These other patients have symptoms in identification with, or out of sympathy for, the target case. Since only the target case has psychopathology, only he or she requires psychotropic drugs as outlined above. It is helpful, however, in order not to shake the confidence of the primary patient, to suggest innocuous topical measures such as baths and emollients for the secondary patients. Their symptoms will resolve in parallel with those of the target case.

What is the Evidence?

Freudenmann, RW, Lepping, P. “Delusional Infestation”. Clin Microbiol Rev. vol. 22. 2009. pp. 690-732. (This is a very comprehensive review of the literature concerning Delusions of Parasitosis. It has perhaps a psychiatric focus that is a little detailed for the practising dermatologist, but it contains a great deal of relevant information.)

Lyell, A. “Delusions of parasitosis”. Br J Dermatol. vol. 108. 1983. pp. 485-99. (A relatively early, empathic and readable review of DOP as experienced by British dermatologists.)

Tampa, M, Sarbu, MI, Matei, C. “Kyrle’s Disease in a patient with delusions of parasitosis”. Rom. J. Intern. Med. vol. 54. 2016. pp. 66-69. (Demonstrates the evolution of delusional ideation.)

Munro, A. “Delusional disorder, somatic subtype, with dysmorphic delusion”. Delusional disorder. Paranoia and related illnesses. 1999. pp. 81-103. (Nicely presented case reports of the different types of somatic delusions that are seen in clinical practice.)

Lee, CS, Koo, JYM. “The use of psychotropic medications in dermatology”. Psychocutaneous medicine. 2003. pp. 427-51. (Many non-psychiatric physicians are not comfortable with prescribing psychotropic medications. This chapter gives dosage, necessary tests, and common side effects of a useful spectrum of appropriate drugs.)

Nasrallah, HA, Tandon, R, Schatzberg, AF, Nemeroff, CB. “Incidence of adverse reactions to classic antipsychotics at therapeutic doses”. The American Psychiatric Publishing Textbook of Psychopharmacology. 1990. pp. 548-9. (This provides a reassuring comparison of the side effects of pimozide as compared with haloperidol.)

Driscoll, MS, Rothe, MJ, Grant-Kels, JM, Hale, MS. “Delusional parasitosis: A dermatologic, psychiatric and pharmacologic approach”. J Am Acad Dermatol. vol. 29. 1993. pp. 1023-33. (This paper gives a very accurate description of the many features commonly noted in the clinical presentation of this disorder , and offers ways to develop the positive doctor-patient relationship crucial to successful treatment.)

Koblenzer, CS. “The challenge of Morgellons diseas”. J Am Acad Dermatol. vol. 55. 2006. pp. 920-22. (Much information available on the Internet, in the media and in the literature suggests a separate etiology for this disorder. This paper argues that what has been termed Morgellons disease is simply a different interpretation of the symptoms experienced in delusions of parasitosis. A similar approach to treatment is ourlined.)

(It is useful to know what is being published, how human experience is being "medicalized", and what one's patients are reading.)

Bjornsson, AS, Didie, ER, Phillip, KA. “Body dysmorphic disorder”. Dialogues Clin Neurosci. vol. 12. 2010. pp. 221-32. (A good review of presentation, treatment and outcome.)

Conrado, LA, Hounie, AG, Diniz, JB, Fossaluza, V, Torres, AB, Miguel, EC, Rivitti, EA. “Body dysmorphic disorder among dermatologic patients: prevalence and clinical features”. J Am Acad Dermatol. vol. 63. 2010. pp. 235-43. (General dermatology patients and those seeking cosmetic treatment were interviewed by a psychiatrist and a dermatologist. The high incidence and lack of prior diagnosis of, and lack of knowledge about BDD in cosmetic patients is noted. The need for accurate diagnosis, patient education, and realistic goals is stressed.)