Intrapleural silicone granuloma mimicking pleural malignancy

We describe a 78-year-old initially presenting with left breast cancer, status post mastectomy and bilateral dual-lumen breast implant placement, subsequently developed lung cancer years later status post lobectomy, who later developed FDG-avid pleural nodularity and thickening. The differential diagnosis of pleural thickening and nodularity can be broad, including metastatic cancer, asbestos-related pleural disease, loculated fluid (including simple pleural effusion, hemothorax, or chylothorax), and pleural infection. However, in the setting of two different primary malignancies, our patient's FGD-avid pleural thickening was concerning for metastatic disease. Further workup with a core-needle biopsy of the pleural nodule revealed "droplets of foreign material and foreign body giant cell reaction consistent with contents of ruptured medical device", without evidence of malignancy. Prior imaging did not indicate breast implant compromise. A subsequent mammogram suggested findings of bilateral implant rupture, however, no further clinical workup was performed. A screening mammogram a decade later indicated possible extracapsular silicone within the right breast and left mastectomy site and an MRI was recommended for further workup. Subsequent MRI showed bilateral extracapsular silicone implant rupture with a thick layer of silicone signal within the left pleura in a similar distribution to her pleural thickening and nodularity. Her breast MRI findings, in conjunction with her pleural biopsy result, are concordant with pleural silicone granulomas from extracapsular breast implant rupture via radio-occult tract from prior left lobectomy procedure.