Granulomatous lobular mastitis (GLM) is a rare, but benign inflamatuary process with unknown underlying etiology. It is typically seen in young women. Painful breast masses, draining sinuses, scarring, and breast atrophy are the main clinical manifestations. This disease is a challenge for clinicians to diagnose and manage. 30 years old and 14 weeks pregnant woman admitted to our clinic with the progressing complaints of a big breast mass, scarring and infectious liquid stream, despite a long term antibiotic treatments. GLM is thought to result from obstruction and rupture of breast lobules. She suffered different side effects from several prescribed treatments and endured a inconclusive recovery. The authors aimed avoid to missdiagnose, such as having bacterial or fungal infections, especially tuberculosis, and perform unneccesary treatment. Idiopathic granulomatous mastitis is a rare unusual condition of unknown etiology. Pathological confirmation is required for its diagnosis and optimal management is still unclear, espically in a pregnant woman.