I am a 62-year-old male. Five years ago, I rather suddenly lost a strip of hair on one side of my head (actually starting with a patch of lost hair in the eyebrow, and extending up past the crown).
It has never come back despite treatment by a dermatologist and attention to diet, rest, combating stress, etc.
Does anyone have any ideas as to what could cause this type of hair loss, clearly unrelated to typical male pattern baldness?