A small skin sample taken from the scalp and examined under a microscope. It is the gold standard for diagnosing uncertain or scarring hair loss, distinguishing conditions like lichen planopilaris from pattern loss when the cause isn't clear from examination and trichoscopy alone.
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Not medical advice. General education only; it does not replace diagnosis or treatment by a licensed professional. Consult a board-certified dermatologist before starting, stopping or changing any treatment.
⚠️ When to see a doctor — don’t self-treat
- Sudden patchy or circular bald spots
- Redness, scaling, pus, pain or itch (possible scarring alopecia — treat urgently)
- Broken hairs or rapid loss
- Loss with body-wide signs (weight loss, fatigue, cycle changes, acne, extra hair)
- Loss right after a new medication
- Any hair loss in a child