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Sir,

I would like to share the interesting case of a 58-year-old lady who presented with the complaint of crawling sensation in her mouth for the past 6 months. She believed that her sensation was caused by numerous small worms inhabiting her complete denture and feeding on her oral tissues. The crawling sensation persisted even if the denture was removed because ‘the worms have penetrated into the oral mucosa.’ Her medical history was unremarkable and she didn't smoke tobacco, drink alcohol, or use recreational drugs. Extra-oral examination was unremarkable and the patient denied any similar sensation elsewhere in her body. Intra-oral examination revealed healthy oral tissues with no evidence of mucosal infection or inflammation (Figure 1 A). Her complete denture was overly clean as she reported washing it with a denture cleanser more than 10 times per day in an attempt to kill the worms (Figure 1 B). The patient reported that she had three different sets of complete dentures since the onset of her symptoms, but all were inhabited by worms. Relevant investigations, including complete blood count, hepatitis serology, vitamin B12, thyroid function, blood sugar, brain MRI, and allergy tests, were within normal range. One week after the initial assessment the patient brought a small envelope containing cloth fibres believing that these fibres were the worms inhabiting her denture and eating her oral tissues (Figure 1 C). The patient was referred to psychiatry where a diagnosis of delusional parasitosis was confirmed.

Figure 1
figure 1

Healthy oral tissues

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Figure 2
figure 2

Two sets of overly cleaned dentures

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Figure 3
figure 3

Cloth fibres brought by the patient and believed to be “evidence” of worm infection

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Delusional parasitosis, also known as Ekbom's disease, is a rare psychiatric disorder characterised by the firm belief of having been infected by parasites, worms, insects or other living organisms when one is not.1 The condition may exist as an isolated phenomenon (i.e. primary delusional disorder) or in association with other psychiatric or organic diseases (i.e. secondary delusional disorder).2 The diagnosis of delusional parasitosis can be made on the basis of history alone, but when the mouth is involved the dentist should perform proper examination to make sure that the patient doesn't have an organic oral disorder. Close collaboration with psychiatry is essential because patients with delusional parasitosis often reject psychiatric referrals.

This letter originally published in the BDJ (2018; 224 : 918, 22 June 2018).