I'm the chairman of the Dutch Society of Tietze- and costonchondritis patients, which is affiliated to the Dutch Rheumatic Patients Society. (see http://www.tietze.nl, also in English, German and French).
Tietze (and costochondritis) are Rheumatic deseases, but are not accepted and treated as so.
For 35 years now, my live has been dominated by Tietze and it still does. However, I've learned to live with it and I mostly can manage that very well. What I'll never accept is the fact that still no doctor or specialist seems to be interrested in deeply investigating all about this sometimes very painfull syndrome. For instance: what causes it, is prevention possible, how (and how fast) is the diagnosis been set, what's the most acceptable and most lasting treatment and what's the best medication, what are the effects of Tietze on the quality of anyones privat- and working live, why do I always have to explain to my medical insurance that Tietze is a real Rheumatic desease? and so on.