Differential Diagnosis
- Single Most Likely Diagnosis
- Obsessive-Compulsive Disorder (OCD): The patient's preoccupation with being infected with HIV, ritual cleaning, and past history of checking compulsions are all characteristic of OCD. The fact that symptoms have persisted despite treatment with SSRI and CBT also supports this diagnosis.
- Other Likely Diagnoses
- Anxiety Disorder: The patient's anxiety and preoccupation with illness could also be indicative of an anxiety disorder, such as generalized anxiety disorder or illness anxiety disorder.
- Major Depressive Disorder: The patient's disheveled and unkempt appearance, as well as their inability to complete college due to symptoms, could suggest a depressive disorder.
- Substance Use Disorder: The patient's use of marijuana to improve anxiety symptoms could indicate a substance use disorder, particularly if they are using it as a coping mechanism.
- Do Not Miss Diagnoses
- Psychotic Disorder: Although the patient does not appear to have delusions or hallucinations, it is essential to rule out a psychotic disorder, such as schizophrenia, which could present with disorganized thinking and behavior.
- Neurodegenerative Disorder: The patient's motor tics as a child and current preoccupation with illness could be indicative of a neurodegenerative disorder, such as Huntington's disease, although this is less likely.
- Tourette's Disorder: The patient's history of motor tics as a child could suggest Tourette's disorder, which often co-occurs with OCD.
- Rare Diagnoses
- Hypochondriasis: Although this diagnosis is now subsumed under somatic symptom disorder or illness anxiety disorder in the DSM-5, it is still worth considering as a rare diagnosis.
- Body Dysmorphic Disorder: The patient's preoccupation with being infected with HIV could be related to a preoccupation with their body or appearance, which is characteristic of body dysmorphic disorder.
- Neurodevelopmental Disorder: The patient's history of motor tics and current symptoms could suggest a neurodevelopmental disorder, such as autism spectrum disorder, although this is less likely.