 [ Symptoms ] tumor on lung pet scan show suspicious but no cancer diagnsis what cam it be [ Disease ] she is allergic to something most likely you and her allergist have notfound it quite yet and may never find it some hives are caused by changes in temperature like getting too warm it is not necessary to know the cause of the hives in order to treat it successfully with antihistamines i know hives can be frustrating but it can be very very difficult even impossible to find the one or many causes