Alopecia Areata

A 28-year-old woman presents with sudden onset of patchy hair loss over the scalp for the past 3 weeks. On examination, she has three well-demarcated, round areas of complete alopecia on the vertex and temporal regions. The scalp is otherwise normal without erythema or scaling. Pull test is positive in the affected areas, and dermoscopy reveals exclamation mark hairs at the margins. She denies any systemic symptoms. Her past medical history includes vitiligo diagnosed 5 years ago. What is the most likely diagnosis?

The clinical images provided demonstrate multiple well-demarcated, smooth patches of non-scarring hair loss on the scalp in different individuals. Which of the following is the most likely diagnosis?

A 28-year-old woman presents with sudden-onset, round patches of complete hair loss on the scalp. On dermoscopy, the structure marked **A** shows tapered hairs that are narrower proximally and broader distally, resembling an inverted exclamation point, at the active edge of the patch. The skin within the patch is smooth with no scaling, erythema, or scarring. Which of the following best explains the pathophysiology of this finding?

A 24-year-old female presents with a sudden, well-defined patch of hair loss on her parietal scalp noticed 3 weeks ago. She denies itching, scaling, or pain and has no history of traction or chemical treatments. She has a personal history of atopic dermatitis and a family history of autoimmune thyroiditis. Examination reveals a single round 3 cm patch of complete hair loss with a smooth, non-scaly, non-erythematous scalp surface. Trichoscopy of the patch border reveals short (2–3 mm) hairs that are broader distally and taper toward the scalp, as marked by **A** in the diagram. The pull test is positive at the periphery, and nail examination shows fine pitting. What is the most likely diagnosis?

A 28-year-old woman presents with sudden onset of hair loss over the scalp for the past 3 weeks. On examination, she has multiple round, well-demarcated patches of complete alopecia on the vertex and temporal regions. The scalp appears smooth without scaling or erythema. Pull test is positive at the margins of the lesions. She denies any systemic symptoms, fever, or recent infections. Her past medical history is significant for vitiligo diagnosed 5 years ago. Laboratory investigations including CBC, thyroid function tests, and serology for syphilis are all normal. What is the most likely diagnosis?