A Rare Case of Non-Hodgkin B-Cell Lymphoma Following Invasive Lobular Carcinoma of the Breast: A Case Report.

The association between breast cancer and non-Hodgkin lymphoma of the spleen is extremely rare, with very few cases documented in the medical literature. We present the case of a 39-year-old woman in good health but with a family history of breast cancer, who, in 2017, developed invasive lobular carcinoma in her right breast, which was treated with mastectomy followed by hormonal therapy. In 2024, she presented with a suspicious right axillary mass, suspected of recurrence, which was confirmed by fine-needle aspiration biopsy. The patient received neoadjuvant chemotherapy, followed by axillary lymph node dissection and bilateral adnexectomy. CT and PET scans showed suspicious splenic lesions suggestive of metastases. Infectious and hematological tests were negative, leading to the decision to perform laparoscopic splenectomy. Histological examination revealed follicular B-cell non-Hodgkin lymphoma. The patient is now in good general condition and is on a biannual follow-up. The case highlights the diagnostic complexity of tumor recurrences and the need to consider alternative diagnoses other than metastasis in oncological patients.