hi i think hairless bald patches ithe scalp is called alopecia areata
.it is got varied etiology.i think it is immunological.nutritional and autoimmune disorders
can also be attributed with it.it is associated with thyroid
disorders or pernicious anaemia.
Pull out test is main test to confirm it where we will able to see exclaimatory hair.it can be treated with pulse therapy of steriods like betametamethasone 2 mg twice a week for 4-6 weeks.application of clobetasol
lotion,melanocyl lotion and follica hair tincture and minoxidil
if not cured by all this procedures go for intralesional triancilone acetonide once in fortnight for 3 to 4 times