What else do you consider in the differential diagnosis for pulmonary-renal syndromes if there is low clinical and serologic evidence of AAV, Goodpasture's or other rheumatologic disease (SLE, RA, APS, Scleroderma)?  

Endocarditis can mimic vasculitis and can have pulmonary hemorrhage. You CANNOT miss that one. Sarcoidosis is I suppose a pulmonary renal syndrome. Renal vein thrombosis from MGN with a pulmonary embolus is I suppose a pulmonary-renal syndrome.

Follow up to Dr. @Rodby. Spot on. Adam Brown has so elegantly discussed on his Podcast Ruminations many times, that endocarditis is the MUST rule out given its propensity for renal involvement and on occasion rt side endocarditis for septic embolic pulmonary infection (NB some patients have pulmona...