Have hair loss which derm thinks telogen effluvium, so then why is hair on my legs, eyebrows, under arms, etc. not falling out and still growing?

Unknown: There is little or no research money for telogen effluvium. It is quite variable and often is patchy on the scalp. In severe cases it can effect body hair, axillary hair, pubic hair, eyelash and eyebrow hair. No-one knows how to explain the differences. Does the Dr speculate about the reason for your case? You left out all the interesting details.