Background: Extranodal lymphoma are rare, in particular, breast non-Hodgkin's lymphoma has an impact of lower 0.5%. It is difficult to diagnose during the pre-operative period, since it can be confused with breast carcinoma.
Case report: A 52 years old female patient was sent due to a lump in her left breast identified in a mammogram. A study was conducted with supplementary tests, being eventually diagnosed as low-grade B-cell follicular lymphoma. She was subjected to a mammary and axillary radioguided occult lesion localisation (ROLL). After, radiation therapy was delivered.
Conclusions: It is a very rare pathology, therefore, there is not relevant research to show effective treatment or diagnosis.