Have you seen rheumatoid nodules or RA-ILD in patients with seronegative RA?

By definition, rheumatoid nodules are considered to be a highly specific manifestation of RA. Regarding the first part of the question, one should never see true rheumatoid nodules in someone who does not have seronegative RA. Though there are sporadic case reports of finding these nodules in people without RA, I think it is safe to say that their presence overwhelmingly implies seropositive RA. Biopsy proven rheumatoid nodules have been rarely seen in adolescents who present with nodules sine RA. Some of these individuals have gone on to develop full blown RA. But this scenario is extremely rare.

Regarding RA-ILD in patients with seronegative RA, I think this can be seen in some individuals who have other rheumatologic conditions that may ...

I have a few patients with subcutaneous RA nodules who have seronegative RA. I often repeat the serologies because as stated above, you would expect these patients to be seropositive. If the patient is a smoker, this facilitates nodule formation. I believe ILD or "RA lung" in true seronegative RA is rare but I have seen it as well. I agree with the comment that you should look for an overlap syndrome in such patients.