EXTRAOSSEOUS GIANT CELL TUMOR ARRISING IN BREAST TISSUE WITH FATAL OUTCOME: A CASE REPORT AND REVIEW OF LITERATURE.

Extra-osseous giant cell tumor (GCT) is a rare tumor that arises in superficial and deep soft tissue morphologically. Extra-osseous GCT arising in breast is exceedingly rare with only 5 reported cases. We report a case of a malignant GCT originating in breast from a 46-year-old patient. Imaging and needle biopsy couldn´t exclude malignancy, excisional biopsy was performed, lesion showed a multinodular architecture, ovoid mononuclear cells and osteoclastic giant cells. Final diagnosis was malignant GCT, with deep surgical margin positive for neoplasia.A radical mastectomy was performed, with surgical bed marking and axillary dissection. 2 lymph nodes out of 20 showed metastatic disease. Resection margins were free of cancer.  Extraosseous GCT is a rare neoplasm. Various localizations have been reported, including salivary glands, uterus, bladder. Four cases of malignant extra-osseous GCT arising in breast tissue have been reported, one with associated to aggressive behavior and a fatal outcome.