To investigate the diagnosis and treatment of granulomatous mastitis with erythema nodosum in lower limbs caused by Corynebacterium tuberculosis.

The diagnosis and treatment process of a patient with granulomatous mastitis caused by Corynebacterium tuberculosis complicated with erythema nodosum in lower limbs admitted to Zhejiang Provincial People’s Hospital on March 28th, 2022 was analyzed and related literatures were reviewed.

This case was a 30-year-old young female patient who was admitted to Zhejiang Provincial People’s Hospital for a half-month period of pain due to the left breast mass. The oral cefuroxime axetil had poor anti-infective treatment effect. The diagnosis was confirmed by histopathology, puncture fluid culture and 16S rRNA sequence analysis as granulomatous mastitis caused by Corynebacterium tuberculosis with erythema nodosum in lower limbs. The results of drug sensitivity test showed that vancomycin and linezolid were sensitive. Subsequently, abscess incision and drainage combined with drug treatment (linezolid and prednisone) were performed, and the mass reduced significantly and the inflammation improved, and the patient was discharged.

Granulomatous mastitis complicated with erythema nodosum of lower limbs caused by Corynebacterium tuberculosis infection is rare, which is easy to be misdiagnosed and mistreated. Bacterial/fungal culture, 16S rRNA sequence analysis and drug sensitivity test should be combined to identify the pathogenic bacteria and carry out targeted anti-infective treatment.