To review other uncommon breast cancers besides those originated from a mammary epithelial cell which may manifest as diagnostic challenging lesions; To show some of those rare breast tumor subsites in correlation with their imaging characteristics; To exhibit uncommon breast tumors from our institution in order to illustrate differential diagnosis for radiologists.

Despite the majority of breast lesions originate from the epithelial tissue, there are also breast tumors that develop out of breast ‘soft tissue’ cells. These tumors range from benign to highly malignant and from very common to extremely rare. Until they are properly diagnosed they may give an appearance of a conventional breast cancer tumor. These uncommon breast cancers can originate from mesenchymal tissue (vascular, lipomatous, nerve sheath, myofibroblastic, and myogenic lesions), skin appendages, thoracic muscle, lymphatic system, and systemic cancer metastases. The exhibit cases...

Mammary stroma (Figure 2): Mesenchymal lesions of the breast comprise a spectrum of lesions that arise in the stroma of the breast. They include fibro-epithelial, fibroblastic and myoblastic, vascular, lipomatous, neural, myogenic, and osseous tumors. Some of these lesions are fairly common, while other lesions are extremely rare with no known prevalence and only a few cases report in the literature. 1. Blood vessels (Figure 3) Haemangiomas are the most common benign vascular tumorof the breast. They typically measure less than 2,0 cm and most...

Although these lesions are uncommon, radiologists must be familiar with those tumor types in order to contribute to a prompt and accurate diagnosis, collaborating to proper management and correct treatment.

C. S. Kiebert; São Paulo/BR - nothing to disclose P. H. H. Souza; São Paulo/BR - nothing to disclose T. C. D. M. Tucunduva; São Paulo/BR - nothing to disclose H. D. Skaf; São Paulo/BR - nothing to disclose D. Y. Otto; São Paulo/BR - nothing to disclose A. B. Onofre Chen; São Paulo/BR - nothing to disclose L. W. Souza; São Paulo/BR - nothing to disclose C. Shimizu; São Paulo, SP/BR - nothing to disclose N. de Barros; São Paulo, SP/BR - nothing to...

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