Granulomatosis with polyangiitis (GPA) involves upper and lower respiratory tracts and kidneys. Lung involvement is among the most important organ involvements in GPA. GPA's lung involvement might be confused with other granulomatous conditions with lung involvement. In this report, we presented clinical features of two cases with GPA who had been diagnosed as tuberculosis (TBC) and well treated with anti-tuberculosis (anti-TBC) drugs. However, one of two cases had ear-nose-throat (ENT) manifestations before the diagnosis of TBC and her extrapulmonary findings related with GPA have added to clinical features in the following years. In the second case, the manifestations of GPA appeared after 13 months of anti-TBC treatment. We speculated that lung involvement in these cases may be due to GPA rather than TBC. Our aim was to highlight difficulties in the differential diagnosis between GPA and TBC and suggest the possible beneficial effect of anti-TBC drugs on the lung involvement due to GPA in light of the literature data.