We have described the unusual mammographic and sonographic findings of foreign body granuloma of the breasts arising after the injection of unknown foreign materials and presenting at screening mammography as bilateral spiculated masses. It has been reported that at mammography, foreign body reactions can appear as calcifications or a mass which simulates malignancy due to its partially circumscribed or ill-defined margin (2
). Reported foreign matter has included suture materials, carbon particles used for the localization of a nonpalpable breast lesion, and gunpowder. In both our cases, bilateral spiculated masses were observed at presentation; in one case there were associated microcalcifications within the mass, and malignancy was thus strongly suspected. Both patients had undergone direct injection of foreign materials into the breast for cosmetic purposes.
Several published reports have described the mammographic findings associated with the injection of foreign materials into the breasts. Silicone granulomas have been depicted as multiple rounded opaque masses (5
), and paraffinomas as dense, streaky opacities causing bizarre architectural distortion and, often, amorphous ring calcifications (6
). Both types of granuloma often involve the whole breast diffusely. At mammography, silicone granulomas or paraffinomas can be diagnosed easily, without the need for histologic diagnosis. Our cases are unique in that the granuloma appeared as a single spiculated mass, present in both breasts. One patient (case 2) told us that the injected material had been paraffin, but the other (case 1) did not remember the kind of injected material. Although the direct injection of silicone or paraffin is illegal, the technique has been used for breast augmentation for several decades. The peculiar finding in our cases may be interpreted as the result of various illegal injection methods. This is the first published case report in which mammography revealed a foreign body granuloma as a single spiculated bilateral mass. In case 1, the patient initially denied having injected her breasts with foreign material, and at first, correct diagnosis was thus not possible. Because such injection is illegal, patients often conceal the fact that it has occurred.
Histological examination revealed groups of cholesterol crystals encased by histiocytes and giant cells, with surrounding granulomatous zones of histiocytes, lymphocytes and plasma cells, and a fibroblastic reaction, similar to that seen in cholesterol granuloma. Cholesterol granulomas occur most commonly in the middle ear and mastoid process, resulting from a foreign body response to cholesterol crystals which involved local tissue breakdown or blood (7
). In the breast, cholesterol granuloma can develop as the late sequela of mammary duct ectasia (8
Sonography revealed that in our cases, deeply located hypoechoic masses were present, and one had invaded the pectoralis muscle, which is unusual even in malignancy. MR imaging of the mass in case 1 demonstrated low signal intensity on T1- and T2-weighted spin-echo images and rapid enhancement, as would be expected with cancers. Delayed images, however, showed peripheral enhancement and central washout, a centrifugal enhancement pattern, in other words, and one not observed in cancers (). Generally, breast cancers enhance from the periphery to the center, and there is peripheral washout (10
). Our cases, in which the histopathologic findings indicated the presence of a fibrotic mass, were also different from those in which fibrosis occurs in an irradiated breast, in which enhancement is not observed (11
). A large number of vessels surrounded by fibrosis might explain the enhancement observed after gadolinium administration ().
The signal intensity of the paraffin-containing round component has been reported as characteristically low on both T1- and T2-weighted images and is markedly suppressed on fat-suppression images (6
). The signal intensity of silicone is reported to be low on T1-weighted images but high on STIR images (5
). In our cases, however, because histopathologic examination showed that the mass consisted primarily of fibrosis and cholesterol clefts, with no identifiable oily materials, the low signal intensity observed on all spin-echo images seems to be due to fibrosis.
We have described this unusual manifestation of a benign lesion developed in reaction to a foreign body. Mammography and sonography both indicated that the bilateral spiculated masses were located in the posterior portion of the breast. Although the imaging findings strongly suggested malignancy, preoperative histologic confirmation by means of large core-needle biopsy helped prevent unnecessary radical mastectomy and led to appropriate treatment.