Understanding of the anatomy of the axillary lymph nodes is important in diagnostic and treatment procedures for breast cancer. An interesting case is presented here of breast cancer without a breast tumour. The first symptom of the disease was lymphadenopathy of the axillary region. This kind of case is extremely rare in clinical practise (one case per 1-5 years) and constitutes a great problem for specialists, since in many cases the primary neoplasm source is unknown. The anatomical and clinical implications of such a situation are discussed.