Dear Editor,
Lymphadenopathy in patients with silicone breast implants represents a diagnostic challenge, especially in oncologic follow-up. We report a case of a 66-year-old woman with breast cancer presenting with 18F-fluorodeoxyglucose (FDG)-avid lymph nodes on positron-emission tomography/computed tomography (PET/CT). Dual-energy CT (DECT) identified silicone deposition in these nodes, subsequently confirmed histopathologically. DECT can thus serve as a valuable adjunct in distinguishing silicone-induced lymphadenopathy from metastasis, potentially avoiding unnecessary invasive procedures.
The 66-year-old patient had a history of right breast cancer treated with bilateral mastectomy, silicone breast implant reconstruction, and chemotherapy. During oncologic follow-up, a control chest CT demonstrated lymphadenopathy in the left axillary, internal thoracic, and cervical lymph-node chains, along with mediastinal enlargement. An FDG PET/CT examination revealed hypermetabolic activity in multiple nodal stations [Figure 1a, c, e]. Subsequently non-contrast DECT images were acquired using the Siemens virtual non-contrast liver material decomposition algorithm on a Siemens Somatom Force scanner (100/Sn140 kV), acquired 2 weeks after the PET/CT study. The colour-coded spectral maps demonstrated red/orange signals at several nodal stations (mediastinal, internal thoracic, cervical, and axillary), consistent with silicone deposition [Figure 1b, d, f]. Histopathological analysis of an axillary lymph node confirmed silicone granulomas (siliconomas) secondary to rupture of the left breast implant.
Figure 1.
Axial fused 18F-FDG PET/CT images (a, c, e) and corresponding non-enhanced DECT images processed with the Siemens virtual non-contrast liver material decomposition protocol (b, d, f). (a, b) Images showing a hypermetabolic anterior mediastinal nodule (arrows), which has a silicone signal on the DECT image. (c, d) Images showing a right paratracheal FDG-avid lymph node (arrowheads) with DECT-confirmed silicone content. (e, f) Images showing a left axillary lymph node (circle) with intense FDG uptake corresponding to silicone deposition on the DECT image
Silicone lymphadenopathy is an important differential diagnosis in patients with breast cancer and implantation histories with newly identified lymphadenopathy, especially in typical drainage pathways. Silicone can migrate into the breast tissue and adjacent chest wall muscles and to regional lymph nodes. Imaging is important to distinguish reactive lymphadenopathy related to silicone deposition from metastatic disease.[1] Although 18F-FDG PET/CT is used widely in oncological imaging, it lacks specificity for the differentiation of benign inflammatory processes, such as siliconomas, from true malignant nodal involvement.[2,3] Once silicone has migrated into the regional lymph nodes, a granulomatous reaction may occur, occasionally resulting in false-positive 18F-FDG PET findings.[3] DECT uses two different energies to delineate structures based on differences in their physical density (g/cm3) and atomic number (Z). Silicone, which contains the atomic element silicon (Z = 14), has a different physical density and atomic number than do surrounding soft tissues, which are composed predominantly of lighter elements (hydrogen [Z = 1], carbon [Z = 6], and oxygen [Z = 8]). Based on these differential properties, tissue decomposition can be used to distinguish silicone from other soft-tissue structures, such as tumoural tissue, on CT images.[1,3] The characteristic spectral signature of silicone, namely, intense colouration on iodine overlay maps due to spectral mismatch, allows for the use of DECT to identify the presence of silicone with high confidence, even without intravenous contrast.[3,4] Although breast magnetic resonance imaging (MRI) is considered to be the gold standard for the detection of intracapsular and extracapsular implant rupture, it is not optimised for the evaluation of nodal stations beyond the breast and immediate axilla, especially when standard breast coils and sequences are used. Moreover, dedicated silicone-sensitive MRI sequences are not routinely included in oncological protocols.[5] Additionally, DECT may be a reasonable option for patients with MRI contraindications.[1,3] In the oncologic setting, DECT offers the additional advantage of evaluating for distant metastases and silicone-related lymphadenopathy within the same field of view, without requiring contrast administration or prolonging scan time. This makes it a particularly useful adjunct to standard staging protocols in patients with breast implants.
In conclusion, as other imaging methods (CT, PET/CT, and MRI) cannot, in principle, differentiate metastatic from silicone-reactive lymph-node disease, DECT is a promising tool for this differential diagnosis in oncological patients with breast implants. While histopathological confirmation remains the gold standard, a confident DECT diagnosis of silicone lymphadenopathy—especially when clinical and imaging findings are concordant—may obviate the need for invasive biopsy in selected cases.
Author contributions
AKM: Case selection, imaging analysis, literature review, writing and revision of the manuscript, approval of final version. BLM: Case management, imaging analysis, literature review, revision, approval of final version. FMC: Literature review, data collection, draft revision, approval of final version. MAFMF: Literature review, data collection, draft revision, approval of final version. EM: Imaging analysis, critical revision, supervision, main draft preparation, approval of final version.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Conflicts of interest
There are no conflicts of interest.
Funding Statement
Nil.
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