My husband has lost large patches of hair on his thighs and calves, it looks like laser treatment gone wrong.:-)what could cause something like that?

Alopecia: He has a type of condition called alopecia, most likely. There are several different types, and these can by treated by a primary care or dermatology doctor

Alopecia: I am inferring from your question that he has not had a laser hair removal treatment. If he has loss a considerable amount of hair with no apparent logical reason, he should go to a dermatologist office for evaluation. Is not an ultra emergency but is important. Hope this helps.