Severe costochondritis is referred to as Tietze’s syndrome. The two conditions were initially described separately because Tietze’s Syndrome involves swelling of the costal cartilages. It is now recognized that the presence or absence of swelling is only an indicator of the severity of the condition.
A mild amount of costochondritis is caused by inflammation of the costal cartilages, whereas Tietze usually involves swelling of the costal cartilages. By definition, both are costochondritis, with the later, being a severe case of costochondritis.