We appreciate the letter from Dr Castañeda and his group regarding our article on pulmonary hemorrhage (PH) in systemic lupus erythematosus (SLE). Several of their points merit comment. In retrospect, we agree that our patient's initial presentation of dyspnea, pulmonary infiltrates, and scant blood-tinged sputum quite possibly represented an undiagnosed episode of PH rather than mycoplasma pneumonia. This diagnosis was entertained at the time but not pursued because of her rapid improvement on receiving oral antibiotics.
As for the utility of carbon monoxide diffusion as a means of diagnosing PH, we would add that the test depends on a fully cooperative patient. Often, the severity of a patient's dyspnea renders the test results uninterpretable.
Regarding the pathogenesis of PH in SLE, the conclusions by Dr Castañeda and colleagues, like others in the literature, are drawn from finding immune complexes (IC) and electron-dense deposits in postmortem lungs, which had undoubtedly suffered