Hereby, we present the case of a 50-year-old woman with 5-year history of chronic idiopathic myelofibrosis who was referred to our institution after she had noted a lump in the breast. Histological examination of the lesion removed from her left breast yielded the diagnosis of extramedullary hematopoiesis in the breast. On the basis of our experience in this particular patient and on the basis of the data in the literature, we discuss the value of different more or less invasive diagnostic procedures, such as sonography, mammography, fine needle aspiration biopsy and surgical excision with histological examination of removed tissue in obtaining the diagnosis of myeloid metaplasia in breast.