Transition from Illness Anxiety Disorder to Delusional Disorder: A Case Series

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INTRODUCTION

Illness anxiety disorder (IAD) is characterized by excessive worry about having or developing a serious undiagnosed medical condition for at least six months, according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) [1]. The International Classification of Diseases 11th Revision (ICD-11) describes a similar condition as hypochondriasis [2]. This disorder is clinically significant because of its chronic course, distress, functional impairment, and high utilization of health care resources. Both classifications note frequent comorbidity with anxiety and depression. The ICD-11 highlights the risk of progression to somatic delusional disorder, which makes early recognition and adherence to treatment crucial [1, 2]. Delusional disorder is characterized by persistent delusions typically lasting one to three months or longer in the absence of other core psychotic features, with functioning relatively preserved apart from the impact of the delusion. In the somatic subtype, the fixed belief centers on bodily functions or illnesses, such as infestation, organ failure, or foul odor, despite contrary medical evidence [1, 2]. Hypochondriasis should be differentiated from delusional disorder since some patients with hypochondriasis with poor or absent insight may have beliefs that appear to be delusional or are overvalued ideas [2, 3]. The beliefs are more likely to be delusional if there is a greater level of conviction and fixity, and if the clinical presentation is less medically plausible [2, 3].

To our knowledge, the transition from hypochondriasis to delusional disorder is rarely reported. One previously reported case involved a patient with hypochondriasis who developed a monosymptomatic hypochondriacal delusion [4]. In addition, a systematic review showed that approximately 22% of patients with delusional disorders have at least one comorbid anxiety disorder, and anxiety disorders may precede delusional disorders [5]. However, there is a lack of data regarding factors that lead to this transition, which warrants further study to enable earlier recognition and treatment. In this case series, we describe two unique cases of IAD who developed related somatic delusions.

CASE SERIES PRESENTATION

All patients in this case series were diagnosed with the somatic-type delusional disorder according to the DSM-5 [1] and ICD-11 [2]. There was no history of mood, psychotic, or anxiety disorders, nor any chronic medical illness. The study is reported in accordance with the CARE guidelines [6].

Case 1

Patient information

A 45-year-old married female from a low socioeconomic background presented with a two-and-a-half-year history of persistent health concerns regarding a serious throat condition. She initially reported having a deep ulcer that had lasted for approximately six months. This was followed by a year-long preoccupation with the belief that she had a cyst in her throat. Over the following year this progressed to a belief that she had a tumor, triggered by occasional tickling sensations in her throat. She frequently examined her throat in the mirror and repeatedly gargled to check for swelling or redness. She had previously been evaluated by multiple otorhinolaryngologists, and had undergone a recent clinical examination and laryngoscopy, all of which were within normal limits.

Clinical findings (initial)

On examination, the patient appeared anxious and preoccupied with the belief that she had a tumor in her throat. She also demonstrated poor insight into her condition.

Diagnostic assessment (initial)

The patient was diagnosed with IAD (care-seeking type) based on the DSM-5 criteria, and correspondingly with hypochondriasis according to the ICD-11 criteria.

Therapeutic intervention (initial)

Pharmacotherapy and psychotherapy options were discussed with the patient; however, she refused to accept the diagnosis yet insisted on receiving medication. Fluoxetine was initiated and titrated from 20 mg to 40 mg once daily.

Follow-up and outcomes (initial)

Follow-up over two months showed a significant reduction in her checking behaviors and a decrease of her concern about having a tumor in her throat, as reported by her husband; however, she did not engage in psychotherapy.

Diagnostic Assessment (re-assessment at 6 months)

The patient was brought to the emergency department approximately six months later with a one-month history of verbal and physical aggression toward her husband, after he repeatedly refused to take her for evaluation of possible throat cancer. She had discontinued her medications three months earlier.

On examination, she was poorly groomed, irritable, and expressed a firm belief that she had a tumor in her throat, as no sputum was being expelled while coughing or gargling. She believed that the sputum was being absorbed by the tumor, which was causing her throat to decay, unlike before, when she could occasionally expectorate. Her husband reported multiple crying spells along with reduced self-care and food intake over the preceding month. Because the duration of the symptoms was less than three months, she was diagnosed with delusional disorder, somatic type, based on the DSM-5 criteria, and with delusional disorder, unspecified, based on the ICD-11 criteria.

Therapeutic intervention (re-assessment at 6 months)

In the emergency department, she was given intramuscular haloperidol (5 mg) and promethazine (25 mg). She was initiated on risperidone (2–6 mg daily), with improvement in symptoms over three weeks.

Follow-up and outcomes (long-term)

The improvement was sustained over three months while she remained on medication. However, her symptoms relapsed one month after discontinuing medication, at the six-month follow-up (approximately one year and two months after the initial presentation).

Case 2

Patient information

A 45-year-old married man from a low socioeconomic background, with premorbid anxious personality traits, a family history of unspecified psychosis in a second-degree relative, and nicotine dependence with abstinence for three years, with no history of chronic medical illness, presented with a five-year history of persistent concerns about having a stomach ulcer and liver failure, triggered by occasional abdominal fullness, discomfort and decreased appetite. He had previously consulted multiple physicians, surgeons, and gastroenterologists and was extensively investigated, including four upper gastrointestinal endoscopies, two colonoscopies, four ultrasound scans of the whole abdomen, and one contrast-enhanced computed tomography of the abdomen — all of which were within normal limits. The patient had been advised to consult a psychiatrist or psychologist. He was diagnosed with hypochondriacal disorder by a physician and was prescribed escitalopram (10 mg) and clonazepam (0.5 mg twice daily), and later sertraline (50 mg) with clonazepam (0.5 mg twice daily). The duration of medication use ranged from two weeks to three months, with some reduction in health-related concerns, but complete relapse of symptoms occurred within months of discontinuation.

Clinical findings

The patient was presented to the outpatient clinic with a firm belief that his liver had failed and that, due to this failure, air from the surrounding environment was being absorbed into his body, polluting it and causing reduced appetite over the past three months. He often became irritable and aggressive when family members or neighbors repeatedly rejected his explanation, and he expressed sadness that none of the doctors he had consulted had addressed his concerns.

Diagnostic assessment

The patient was diagnosed with delusional disorder, somatic type according to DSM-5 criteria and delusional disorder according to ICD-11 criteria.

Therapeutic interventions

Treatment with cariprazine (1.5–3 mg daily) was initiated, resulting in symptomatic improvement within two weeks.

Follow-up and outcomes

The improvement was maintained over four months, but symptoms relapsed within two weeks of discontinuing medication. On restarting cariprazine at 3 mg, his symptoms resolved completely and remained stable for six months, up to the last follow-up.

Informed consent

Written informed consent for publication of clinical details was obtained from the patients, as well as for the publication of any data in this article that could potentially identify them.

DISCUSSION

Both patients were initially diagnosed with IAD and hypochondriasis, and as their illnesses progressed, they began to experience somatic delusions involving the same bodily systems previously associated with IAD. In both cases, the beliefs about having a serious illness, such as a tumor in the throat and liver failure, persisted for more than a month and were held with a strong conviction. These beliefs were implausible and illogical, involved constant preoccupation throughout the day, and were accompanied by low mood and aggression towards others when contradicted. These beliefs also interfered with daily functioning, indicating that they were delusional [6]. The delusions were limited to bodily concerns, without any other symptoms of schizophrenia, and were therefore diagnosed as delusional disorder [1, 2].

A previous case study reported a woman who initially had hypochondriasis and later developed the delusion that “her gastric mucosa dried out and she had a rotten tube in her throat”. She responded to electroconvulsive therapy [4]. Our cases differ from this report. In Case 1, the beliefs about having a throat tumor evolved into a delusion after treatment discontinuation, whereas in Case 2, the patient presented with a delusional conviction of liver failure. The factors leading to the transition from hypochondriasis to somatic delusions remain difficult to determine. However, reasoning biases and a tendency to jump to conclusions may contribute to this progression [7]. Previous studies have shown that anxiety disorders may precede delusional disorders [5], and a case series also demonstrated that four patients with delusional disorder had a prior diagnosis of social anxiety disorder [8]. Dopamine dysregulation and amygdala-prefrontal dysfunction may be contributing neurobiological factors [5, 8]. In addition, poor treatment compliance may play a role, requiring further investigation. Moreover, a family history of psychosis, as seen in Case 2, is a known risk factor for developing psychotic disorders [9]. A similar transition — from distorted health-related ideas to somatic delusions involving the genital organs (Dhat delusion) — has also been described in the literature [10]. This case series highlights the uncommon transition from IAD to somatic-type delusional disorder, contributing to the limited literature on this phenomenon. The detailed timelines illustrate how prolonged health-related worries can evolve into fixed delusional beliefs, emphasizing diagnostic challenges and the importance of treatment adherence. The cases also demonstrate the effectiveness of antipsychotic medications and highlight potential vulnerability factors, such as premorbid anxious traits and family history of psychosis. However, the small sample size, lack of standardized assessments, short follow-up duration, and differing treatment approaches limit generalizability, and causality for the transition remains speculative.

Both patients and their family members acknowledged the importance of treatment adherence. They also reported that relapses were marked by poor self-care, emotional distress, and strained family relationships, whereas sustained treatment led to symptomatic remission.

CONCLUSION

In the context of poor treatment adherence and a family history of psychosis, the cases show how hypochondriacal thoughts may evolve into somatic delusions. It is also critical to distinguish delusional disorder from hypochondriasis, particularly in cases with poor or absent insight. Further research is needed to explore the factors that may predispose patients with hypochondriasis and poor treatment adherence to develop delusional disorder or other psychotic disorders.

 

Authors’ contribution: All the authors made a significant contribution to the article, checked and approved its final version prior to publication.

Funding: The research was carried out without additional funding.

Conflict of interest: The authors declare no conflicts of interest.

Generative AI use statement: Nothing to disclose.

About the authors

Debanjan Bhattacharjee

Central Hospital Dhori

Author for correspondence.
Email: debanjanbhatta93@gmail.com
ORCID iD: 0000-0002-7431-0189

MBBS, MD (Psychiatry), Specialist Psychiatry

India, CCL, Jharkhand

Amrita Chowdhury

Gouri Devi Institute of Medical Sciences and Hospital

Email: debanjanbhatta93@gmail.com

MBBS, MS (ENT), Assistant Professor

India, Durgapur

References

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