Differential Diagnosis for 10-year-old Male Patient with New-onset OCD-like Symptoms and Chronic Constant Nausea

• Single Most Likely Diagnosis
  • Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS): This condition is characterized by the sudden onset of OCD symptoms, often accompanied by other neuropsychiatric symptoms, following a streptococcal infection. The nausea could be a non-specific symptom associated with the underlying infection or the neuropsychiatric condition itself.
• Other Likely Diagnoses
  • Anxiety Disorder: The OCD-like symptoms could be part of a broader anxiety disorder, with the nausea being a somatic manifestation of anxiety.
  • Gastroesophageal Reflux Disease (GERD): Chronic nausea could be due to GERD, and the stress of dealing with a chronic condition might exacerbate or contribute to the development of OCD-like symptoms.
  • Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease or ulcerative colitis can cause chronic nausea and may have extraintestinal manifestations, including psychiatric symptoms.
• Do Not Miss Diagnoses
  • Brain Tumor: Although rare, a brain tumor could cause both neuropsychiatric symptoms (like OCD) and nausea due to increased intracranial pressure or local effects on brain areas involved in emotion regulation and gastrointestinal function.
  • Neurodegenerative Disorders: Certain neurodegenerative disorders, such as Huntington's disease (though exceptionally rare in this age group), can present with psychiatric symptoms and gastrointestinal disturbances.
  • Infections (e.g., Lyme disease, toxoplasmosis): Certain infections can cause a wide range of symptoms, including neuropsychiatric symptoms and gastrointestinal issues.
• Rare Diagnoses
  • Mitochondrial Disorders: These are a group of disorders caused by dysfunctional mitochondria, which can affect any system in the body, including the nervous and gastrointestinal systems, leading to a wide range of symptoms.
  • Wilson's Disease: A genetic disorder that leads to copper accumulation in the body, which can cause psychiatric symptoms, gastrointestinal issues, and other systemic problems.
  • Autoimmune Encephalitis: A condition where the immune system attacks the brain, leading to a variety of neuropsychiatric symptoms, which could include OCD-like symptoms and nausea.