Analysis of misdiagnosis causes and imaging characteristics of granulomatous lobular mastitis

PEI Weiqi; SHI Xiaoguang; ZUO Ximeng

doi:10.3969/j.issn.1002-3429.2026.04.003

Abstract：Objective To investigate the clinical characteristics,causes of misdiagnosis,and imaging characteristics of granulomatous lobular mastitis(GLM).Methods A retrospective analysis was performed on 21 patients with GLM that were initially misdiagnosed with having other diseases and were admitted from July 2020 to July 2024.Results All patients presented with breast mass as the main manifestation,accompanied by pain or skin redness.Nine patients were initially diagnosed with having breast cancer due to palpable hard mass with irregular edge and skin adhesion,and then diagnosed with having GLM by needle biopsy.Seven patients were misdiagnosed with having acute mastitis because of ipsilateral axillary lymph node enlargement and skin redness and swelling.Empirical anti-infective treatment was ineffective,and they were diagnosed with having GLM by histopathological examination.Three patients were misdiagnosed with having breast fibroadenoma by ultrasound because of the clear boundary and regular shape of the mass,and were diagnosed with having GLM by postoperative pathological examination.Two patients were misdiagnosed as breast hyperplasia due to moderate mass texture and periodic pain,and were diagnosed with having GLM by postoperative pathological examination.Ultrasound examination was performed in 21 patients,mammography in 16 patients,and magnetic resonance imaging in 12 patients.Ultrasound showed hypoechoic mass with unclear boundary,with posterior acoustic shadow attenuation.Asymmetric dense shadow with fuzzy or spiculate edge was common in mammography,which was more likely to be misdiagnosed as being malignant.Magnetic resonance imaging showed slightly high signal on T2-weighted imaging,and enhanced scan showed rapid progressive enhancement.The duration of misdiagnosis ranged from 2 to 16 weeks.All patients received surgical treatment after diagnosis,and 16 patients with extensive lesions or abscess were given low-dose Glucocorticoids to control inflammation before operation.All patients were followed up for 3 to 6 months,the clinical symptoms disappeared completely,and no recurrence was found by ultrasound examination.Conclusion The clinical manifestation and imaging characteristics of GLM lack specificity,making it prone to misdiagnosis as breast cancer,mastitis,or mammary hyperplasia.Improving awareness of this disease,combining ultrasound imaging characteristics,and timely pathological examination are key to reducing misdiagnosis.