"Doctor, You Must Examine My Creature Collection!": A Case Report of Delusional Infestation

Abstract

Delusional infestation--either secondary when attributed to a medical condition (including a bon-a-fide parasite infestation) or a pharmacologic agent (prescribed or illicit) or primary when secondary etiologies have been excluded--is a psychosis in which, for at least one month duration, the patient not only has a delusion that an animate organism or an inanimate pathogen has infested them, but also has abnormal tactile sensation (such as pruritus) of their skin caused by the etiology of their delusion. In patients over the age of 50 years, a delusional infestation is three times more common in women than men; however, delusional infestation in younger patients is often secondary, associated with illicit drug exposure, and equally common in women and men. Primary skin lesions are typically absent in delusional infestation patients; however, secondary skin lesions--resulting from the patient's efforts to remove the parasite from their skin--can be observed, such as excoriations, prurigo nodules, scars, and ulcers. Delusional infestation patients typically strive to convince the person evaluating them that their infestation is valid and many of these individuals do this by collecting the parasites in a container. Presentation of the pathogen-filled containers is a pathognomonic feature of delusional infestation that has been referred to as either a positive creature collection sign, match box sign, parasite preservation sign, pillbox sign, or specimen sign. Morgellons disease--in which the pathogen being extruded from the skin is a fiber--has several features (including an excellent response to treatment with antipsychotic agents) in common with delusional infestation; therefore, most investigators consider Morgellons disease to be a variant of delusional infestation. Delusional infestation can be associated with numerous diseases, including comorbid psychiatric conditions. Indeed, up to 15 percent of delusional infestation patients have one (folie a deux) or more individuals with similar symptoms. A man with delusional infestation is described who had a positive creature collection sign, a fixed belief that his symptoms were caused by the infesting organism, and refusal to accept that he had a psychiatric disorder. He insisted that the evaluating dermatologist examine the pathogens in the clear plastic container he brought with him to his appointment. He was convinced that the pruritus of his scalp, eyebrows, and eyelashes was associated with a non-existent lice infestation. Secondary delusional infestation was excluded and his concurrent mild seborrheic dermatitis was treated topically; however, his itching did not resolve. He eventually agreed to seek treatment with a psychiatrist. The management of delusional infestation is based on its etiology; resolving the underlying medical condition or discontinuing the causative pharmacologic agent is the treatment approach for secondary delusional infestation, whereas low-dose antipsychotic agents are the intervention of choice for treating primary delusional infestation.

Keywords: creature collection sign; delusional infestation; delusional parasitosis; delusions of parasitosis; ekbom syndrome; mental health awareness; morgellons disease; parasite preservation sign; psychocutaneous; psychodermatology.

Figure 1. Delusional infestation presenting as scalp pruritus in a man convinced he has pediculosis

The right (A) and left (B) sides of the head of a 63-year-old man, who believed that the persistent itching of his scalp for three months was caused by a lice infestation. Examination of his scalp shows androgenetic alopecia with frontal hairline recession and hair thinning on the crown and both temporal regions. Flakes of keratin (black arrows), consistent with the diagnosis of mild seborrheic dermatitis, are noted on some of the hair shafts; however, neither lice nor nits were observed.

Figure 2. Inanimate material on the eyebrows of a man with delusional infestation interpreted by the patient to be lice

The right (A) and left (B) eyebrows of a 63-year-old man show small keratin flakes (black arrows) that he is convinced are parasites.

Figure 3. A delusional infestation patient believes that the numerous keratin plaques of mild seborrheic keratosis on his eyelashes are parasitic organisms

A 63-year-old man with delusional infestation has several keratin plaques (black arrows) located at the base of his eyelashes on the right (A) and left (B) upper eyelids. He interprets the inanimate material to be lice.

Figure 4. Microscopic examination of eyebrow hair and scalp hair from a man with delusional infestation

Secondary delusional infestation has been excluded in a 63-year-old man with delusional infestation. He neither has a bone-a-fide parasitic infestation nor a medical condition associated with delusional infestation. In addition, he has not received any medications associated with pruritus and he has not been using illicit drugs. Hairs were obtained from his eyebrow (A) by plucking and his scalp (B) by pulling.  After placing the hairs on glass slides, they were evaluated using a light microscope. The eyebrow hair (A) has small keratin flakes (black arrows) and the scalp hair (B) has a larger keratin plaque on the hair shaft (within the black oval).

Figure 5. A positive creature collection sign in a man with delusional infestation

A pathognomonic feature of delusional infestation is present when the patient brings their collection of what they are convinced to be pathogenic creatures for the person evaluating them to examine. The 63-year-old man with delusional infestation presented a small, clear plastic container in which he had placed what he believed to be lice that were infesting the hair on his scalp. Inanimate keratin flakes (white arrows) can be observed in the container when it is closed (A) and after it has been opened (B).