Extramedullary lymphoma infiltration of the breast by lymphoblastic lymphoma is very rare and most cases are of B-cell lineage; T-cell neoplasms represent less than 10% of all breast lymphomas. Here, we report one patient with lymphoblastic lymphoma and one patient with leukemia, who have similar lesions in breasts with different ultrasound elastography findings. Ultrasound-guided tru-cut biopsies were performed and the first lesion was confirmed as lymphoma infiltration and the second as fibroadenoma. In cases of breast mass presence in patients with a history of hematologic malignancies such as lymphoma or leukemia, breast infiltration should be kept in mind. Elastography findings can assist in the differentiation of these lesions and further investigations or biopsies can be avoided.