Sentinel node biopsy has become the standard practice in lymph node staging in breast cancer in early stages. However, uncertainty remains regarding the best method of radiotracer/dye injection. Currently, the subareolar injection is being widely used because of its technical simplicity and higher rates of SN location versus the so-called deep techniques (peritumoral, intratumoral) that require greater specialization and greater use of resources in the non-palpable lesions. We present a case of a discrepancy between the two techniques that could have caused a false negative.