RESUMO
BACKGROUND: Granulomatous lobular mastitis (GLM) is a rare benign inflammatory disease of the breast and is classified under comedo mastitis in traditional Chinese medicine (TCM). The etiology of this disease is unknown, and it mainly occurs in women of childbearing age. The diagnosis depends on histopathological biopsy. At present, there is no systematic and standardized treatment plan for GLM. In the absence of evidence supporting an infectious etiology, affected patients might continue to receive multiple courses of antibiotics and unnecessary surgery. CASE SUMMARY: A 37-year-old Chinese woman with a history of coronavirus disease 2019 infection presented with swelling and pain in the left breast. She also had erythema, nodules in the lower extremities, arthritis in both knees, cough, and headache. In the early stage of GLM, the mass was not significantly reduced by conservative treatment with internal application of TCM; hence, surgical treatment was carried out. The aim of postoperative treatment was to drain the pus, eliminate the necrosed tissue, and expand the muscles; fumigation and washing using TCM was applied. CONCLUSION: Combined internal and external treatment with TCM, following the principle of "Prioritize internal treatment before ulceration and emphasize external treatment after ulceration" was effective in our patient with GLM. The prognosis was good. We believe that TCM offered valuable therapeutic benefits in this disease.