a 60-year - old woman presented with an abnormality detected by screening mammography . upon physical examination , we noted a non - tender nodule with a relatively circumscribed margin in the upper outer quadrant of the left breast . the mammograms revealed a 1.5 cm , ill - defined , high - density mass in the left outer breast ( fig . us showed an irregular shaped , ill - defined homogeneous hypoechoic mass with an echogenic halo ( fig . color doppler study showed moderate vascularity in the peripheral halo portion of the lesion ( fig . 1d ) . we classified the mass as breast imaging reporting and data system ( bi - rads ) category 4c ( moderate suspicion for malignancy - estimated probability for malignancy ranging from 50% to 95% ) . next , we performed us - guided automated gun biopsy using a 14-gauge needle and histological examination of the biopsy specimens revealed the presence of an inflammatory pseudotumor . further , excisional biopsy confirmed this diagnosis . upon gross pathology , we did observe an ill - defined pinkish - white mass without necrosis or hemorrhage ( fig . microscopically , we noted irregularly oriented intersecting fascicles of spindle cells at low magnification with hematoxylin and eosin staining . mixed inflammatory cells such as lymphocytes , histiocytes , and plasma cells were infiltrated between the spindle cells . at high magnification , the proliferating spindle cells had bland - looking nuclei and the nucleoli were inconspicuous . we did observe mitoses ( up to 3 of 10 per high - power field ) , however , no atypical mitoses were found ( fig . following an immunohistochemical assay , we found the spindle cells to be reactive for anti - sma ( smooth muscle actin ) and demonstrated myofibroblastic differentiation ( fig . we also found the tumor cells to be negative for a reaction for pan - ck ( pancytokeratin ) , which resulted in the exclusion of the possibility of metaplastic carcinoma . we also found the tumor cells to be negative for a reaction to anaplastic lymphoma kinase ( alk ) ( figure not shown ) . during a two - year follow up period , we did not find any evidence for tumor recurrence at the left breast , as demonstrated by mammographic and us images . inflammatory pseudotumors of the breast are extremely rare ; a literature search yielded only fifteen cases in the english - language literature ( 1 - 10 ) . in all 15 cases , in addition , we found that all the lesions were surgically excised ; however , the three patients showed recurrence after surgery , with two of the three patients having bilateral recurrence ( 2 - 4 ) . the pathogenesis of inflammatory myofibroblastic tumors is controversial ; although , the etiology of this entity remains unclear and is considered by some investigators to have an aberrant reactive or inflammatory response to local cytokines in nature ( 5 , 10 , 11 ) . however , cases with vascular invasion , local recurrence , and even metastasis have been reported ( 5 , 10 - 12 ) . furthermore , the cytogenetic analysis of one case of an inflammatory pseudotumor of the breast showed that the disease was due to clonal proliferation , thus supporting the hypothesis that an inflammatory pseudotumor of the breast is a true neoplasm ( 7 ) as opposed to an exuberant tissue response to inflammation . alk , expressed due to a chromosomal translocation involving 2p23 has recently been demonstrated in some cases of an inflammatory pseudotumor ( 13 , 14 ) . radiologically , our case appeared as an ill - defined mass on mammographic and us examination , which is consistent with cases described by haj et al . however , for most of the previously reported cases , a well - defined border was depicted on mammograms ( 5 ) . there was also one case with a rare imaging finding , where us demonstrated the presence of a focal area of irregularly marginated acoustic shadowing without a mass configuration ( 15 ) . it should be emphasized that the imaging findings of our case were suspicious for malignancy . first , the mass was seen in this case with an ill - defined margin on mammograms and us and the overlying skin was minimally retracted as determined on physical examination , which was also described by haj et al . additionally , we depicted the vascularity in the peripheral halo portion of the lesion on color doppler study . because the mass was located within a fat layer , fat necrosis could be included in the differential diagnosis . in conclusion , we have presented a case of an inflammatory pseudotumor of the breast , which was initially misdiagnosed as being malignant due to the ill - defined border of the lesion on mammograms and us . we should consider surgical excision and a close follow - up due to its tendency to enlarge locally and to recur after excision .
inflammatory pseudotumor , also known as inflammatory myofibroblastic tumor and plasma cell granuloma , is an uncommon low - grade lesion composed of spindle cells admixed with mature plasma cells and other inflammatory cells , such as histiocytes , lymphocytes , and eosinophils . here 
 , we describe the mammographic and ultrasonographic findings of a case of an inflammatory pseudotumor of the breast in a 60-year - old woman . with the suspicion of malignancy , core needle biopsy and surgical excision confirmed the mass as being an inflammatory pseudotumor of the breast .