From dermatological symptoms to psychiatric diagnosis: A case report of delusional parasitosis

Delusional parasitosis is a rare psychiatric disorder characterised by a fixed, false belief of infestation with parasites. This case report discusses a 70-year-old woman with well-controlled Type 2 Diabetes Mellitus who presented with persistent sensations of insects crawling on her skin. Despite extensive dermatological treatments for presumed contact dermatitis, her symptoms worsened, leading to obsessive behaviours such as excessive scratching and the application of alum. Psychiatric evaluation revealed delusions of infestation and tactile hallucinations, resulting in a diagnosis of delusional parasitosis. The patient was treated with Risperidone, starting at 2 mg daily, which led to a significant reduction in symptoms within two weeks. She demonstrated a 70% improvement in delusional beliefs and compulsive behaviours by the end of the third week, with complete healing of her skin lesions observed over subsequent follow-ups. This case underscores the diagnostic challenges posed by delusional parasitosis and highlights the importance of early psychiatric intervention and multidisciplinary collaboration. The report further emphasises the efficacy of antipsychotic treatment in achieving symptom resolution and improving patient outcomes.