Differential Diagnosis for Localized Hair Loss on the Right Side

• Single most likely diagnosis
  • Alopecia areata: This is a common condition that causes patchy hair loss, often on one side of the head. It is an autoimmune disease that can be triggered by stress, genetics, or other factors.
• Other Likely diagnoses
  • Tinea capitis (ringworm of the scalp): A fungal infection that can cause hair loss in a specific area, often accompanied by redness, itching, and scaling.
  • Traumatic alopecia: Hair loss due to mechanical stress, such as tight hairstyles (e.g., braids, ponytails), or excessive heat styling.
  • Androgenetic alopecia (male/female pattern baldness): Although typically more diffuse, it can sometimes present with localized thinning, especially in the early stages.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Secondary syphilis: Can cause patchy hair loss, among other symptoms like rash and fever. It's crucial to consider this diagnosis due to the potential for severe complications if left untreated.
  • Cutaneous lymphoma (e.g., mycosis fungoides): A rare type of skin cancer that can cause localized hair loss, along with other skin symptoms.
• Rare diagnoses
  • Discoid lupus erythematosus: An autoimmune condition that can cause localized hair loss, scarring, and skin lesions.
  • Folliculitis decalvans: A rare inflammatory condition that leads to hair loss, often accompanied by redness, swelling, and pus-filled bumps.
  • Trichotillomania: A psychological disorder characterized by compulsive hair pulling, leading to localized hair loss.