Transient Regression of Breast Carcinoma After Diagnostic Biopsy and Tumor Heterogeneity: A Case Report

Spontaneous cancer regression is a rare biological phenomenon; however, the mechanisms involved in this process are still poorly understood. We report the case of a 92-year-old woman with a histological diagnosis of breast carcinoma. On the date of the scheduled surgical resection of her tumor, she did not present the initial lesion diagnosed by biopsy, on clinical examination. The patient underwent mammography and breast magnetic resonance imaging, which confirmed the absence of the initial tumor. Due to religious beliefs, the patient refused additional specific treatment with her family's approval. In consensus with her family, we proposed imaging follow-up to assess tumor recurrence, which lasted for 18 months. In this article, we discuss the theory that the local trauma generated by the diagnostic percutaneous biopsy triggered an immune response responsible for the phenomenon of tumor regression. The secondary objective is to discuss the transformation in the histological type of tumor cell.