A Case of Pulmonary Tuberculosis Developed During Neoadjuvant Chemotherapy for HER2-Enriched Breast Cancer

In the 1990s, the number of newly registered tuberculosis patients in Japan was about 40,000 per year. It has been gradually decreasing and the number of new patients became 10,235 in 2022 with the incidence rate of 8.2 per 100,000 population. However it is still occasionally encountered even in recent years. Herein, we report a case of human epidermal growth factor receptor 2(HER2)-enriched breast cancer patient developed pulmonary tuberculosis just after finishing neoadjuvant chemotherapy and was successfully treated for both disease simultaneously. A 68 years old woman presented due to right breast mass was diagnosed with hormonal receptor-negative, HER2-positive invasive ductal carcinoma. Neoadjuvant chemotherapy with paclitaxel, trastuzumab and pertuzumab was started. After 12 courses of chemotherapy, CT scan revealed disappearance of the right breast tumor and infiltrating shadow in the left lower lung field. Sputum polymerase chain reaction test for tuberculosis was positive. Anti-tuberculosis chemotherapy was started. Four days after starting isoniazid, partial mastectomy was performed under local anesthesia and radiation therapy for the breast was omitted. There are no signs of recurrence of breast cancer and pulmonary tuberculosis for 5 years. Chemotherapy for breast cancer and premedication with corticosteroid may have inhibited cellular immunity, causing endogenous relapse of tuberculosis.