Granulomatosis with polyangiitis (GPA, formerly Wegener's granulomatosis) can present diagnostic difficulties for the clinician as there can be considerable overlap in features with tuberculosis (TB). Indeed, there are documented cases both of coexisting TB and GPA, and cases wrongly diagnosed as GPA when in fact TB was the underlying diagnosis. This lesson presents a case of GPA where TB was also considered as a differential and highlights the diagnostic and management difficulties when this is the case.