Xanthogranulomatous
inflammation is an uncommon finding in the breast. Sixteen cases of xanthogranulomatous
mastitis were reviewed to determine the characteristic clinicopathological features. Xanthogranulomatous
mastitis involved foamy histiocyte clusters interspersed with inflammatory cells. Foamy histiocytes were bland with small pyknotic nuclei. Xanthogranulomatous
mastitis was associated with
fat necrosis in five cases (31%), multinucleated giant-cell reactions in six cases (38%), and
cholesterol crystals in five cases (31%). In three cases (19%), xanthogranulomatous
mastitis coincided with
ductal carcinoma in situ or invasive
ductal carcinoma. Duct
ectasia with foamy histiocyte aggregates were noted in five cases (31%). It is suggested that the etiology of xanthogranulomatous
mastitis is obstruction and
rupture of the ectatic duct with foamy histiocyte aggregates. In breast core biopsy,
granular cell tumor and invasive
carcinoma such as histiocytoid
carcinoma and
lipid-rich
carcinoma could demonstrate similar pathological features to xanthogranulomatous
mastitis. In conclusion, xanthogranulomatous
mastitis could be encountered in breast core biopsy and surgical excision tissue. Diagnosis of xanthogranulomatous
mastitis can be made by excluding other diseases that elicit xanthogranulomatous
inflammation in the breast. In breast core biopsy, xanthogranulomatous
mastitis could be distinguished from
granular cell tumor, histiocytoid
carcinoma and
lipid-rich
carcinoma by using
cytokeratin and histiocytic marker such as alpha1-anti-trypsin and CD68
stain.