Limited granulomatosis with polyangiitis in an adolescent with Crohn's disease on infliximab therapy: cause or coincidence?

Pulmonary involvement in Crohn's disease (CD) may precede the development of intestinal inflammation, but in most cases occurs during the course of treatment, either as an extra-intestinal manifestation, because of secondary infections, or as a side effect of the therapy itself. This case highlights the differential diagnosis and work up for multiple pulmonary nodules that developed in a patient with CD who had been in remission on infliximab therapy. Even though infectious causes, such as Mycobacteria and Fungi, account for majority of these cases, the possibility of non-infectious conditions such as autoimmune disorders should also be considered.