Locoregional recurrence of triple-negative breast cancer with low tumor-infiltrating lymphocytes: a case report.

Triple-negative breast cancer (TNBC) is an aggressive subtype with high histological grade and an increased propensity for early recurrence. Early locoregional recurrence within three months of a Patey mastectomy is uncommon, making this case noteworthy and contributing valuable insight into the biological aggressiveness of TNBC and the prognostic role of tumor-infiltrating lymphocytes (TILs). We report the case of a 49-year-old postmenopausal woman followed for TNBC at the Mohammed VI Oncology Center in Casablanca, Morocco, who presented with a rapidly enlarging inflammatory mass along the outer edge of the left Patey mastectomy scar, extending toward the axillary tail, three months after surgery. Histopathological evaluation confirmed a locoregional recurrence of invasive carcinoma of no special type, revealing a 12.2 cm grade III tumor with a Ki-67 index of 40%, hormone receptor-negative/HER2-negative status, and low TILs (10%). The patient received neoadjuvant chemotherapy, followed by surgical excision of the recurrent lesion, radiotherapy and adjuvant chemotherapy consisting of capecitabine, vinorelbine, and gemcitabine, with good tolerance and no evidence of distant metastasis during follow-up. This case underscores the prognostic impact of low TILs and highlights the importance of considering the tumor microenvironment in risk stratification and personalized management of TNBC.