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

Illness anxiety disorder, also known as hypochondriasis, is characterized by excessive worry about having or developing a serious medical condition and has rarely been associated with delusional disorder.

Two middle-aged patients with illness anxiety disorder gradually developed somatic-type delusional disorder. The first, a 45-year-old woman, had a two-and-a-half-year history of health-related fears involving her throat - an ulcer for six months, a cyst for one year and a tumor for one year. She initially showed improvement with fluoxetine over two months, but after discontinuing the medication for three months, developed a fixed delusion that she had throat cancer, accompanied by aggression and poor self-care. She responded to risperidone within three weeks, though symptoms relapsed after discontinuing the treatment at six months. The second patient, a 45-year-old man with anxious traits and a family history of psychosis, had a five-year history of concerns about having a gastric ulcer and liver failure despite repeated normal medical evaluations. He subsequently developed a delusional conviction of liver failure for three months and showed improvement within two weeks with cariprazine treatment. He remained stable for four months but relapsed after stopping the treatment. Upon restarting cariprazine, he achieved sustained remission for six months.

The factors leading to the transition of illness anxiety-related ideas into delusions require further study in the context of poor treatment adherence. It is equally important to distinguish delusional disorder from hypochondriasis, particularly in patients with poor or absent insight.