Idiopathic Granulomatous Mastitis: Cytologic and Histologic Study of 65 Egyptian Patients

Background: The etiology of idiopathic granulomatous mastitis (IGM) is unknown, and it is commonly misdiagnosed clinically and/or radiologically as breast cancer. The role of fine-needle aspiration cytology (FNAC) in its diagnosis is still a matter of debate. The aim of the current study is to assess the value of FNAC in the diagnosis of IGM, and to search for the presence of bacteria in IGM with cystic vacuoles, which was described recently by a few authors. Materials and Methods: Retrospective study of cytologic smears and histologic tissue sections of 65 Egyptian IGM cases was done along with microbiologic testing. A comparison of the frequency of IGM in Egypt to that of other populations was also made. Results: IGM has typical FNA features which can easily exclude malignancy. Histologically, cystic vacuoles were encountered in 35 out of 65 cases (53.9%), with only 6 (17.14%) of these cases showing Gram-positive bacilli (GPB). The frequency of IGM in Egypt is comparable to those in other Middle Eastern countries but much higher than in Western countries. Conclusion: IGM is a common breast disease in Egypt. FNAC in IGM has a high diagnostic accuracy. This study supports the few recent studies that have detected GPB in IGM with cystic vacuoles. Thus, bacteriologic examination in such cases may affect the treatment strategy.