Differential Diagnosis for Patchy Nonscarring Hair Loss

• Single most likely diagnosis
  • Alopecia areata: This is the most common cause of patchy nonscarring hair loss, characterized by one or more round, smooth patches of hair loss, often on the scalp. It is an autoimmune condition that can be triggered by stress, genetics, or other factors.
• Other Likely diagnoses
  • Tinea capitis (ringworm of the scalp): A fungal infection that causes patchy hair loss, often accompanied by redness, itching, and scaling.
  • Telogen effluvium: A condition that causes excessive shedding of hair after a major body stress, such as severe illness, major surgery, or psychological stress.
  • Trichotillomania: A psychological disorder characterized by compulsive hair pulling, leading to patchy hair loss.
• Do Not Miss diagnoses
  • Syphilis: A bacterial infection that can cause patchy hair loss, particularly in the secondary stage. It is essential to consider this diagnosis due to its potential for serious complications if left untreated.
  • Lupus: An autoimmune disease that can cause patchy hair loss, among other symptoms. Early diagnosis and treatment are crucial to prevent long-term damage.
• Rare diagnoses
  • Sarcoidosis: A condition characterized by the growth of granulomas in various parts of the body, including the scalp, leading to patchy hair loss.
  • Lichen planopilaris: A rare inflammatory condition that causes patchy hair loss, often accompanied by redness, itching, and scaling.
  • Discoid lupus erythematosus: A chronic skin condition that can cause patchy hair loss, particularly on the scalp, due to inflammation and scarring.