Fluorodeoxyglucose-positive internal mammary lymph node in breast cancer patients with silicone implants: Is it always metastatic cancer?

Objectives: Patients with breast cancer following mastectomy and silicone implant reconstruction may have enlarged internal mammary lymph nodes with pathological uptake on positron emission tomography with ¹⁸F-fluorodeoxyglucose. This lymphadenopathy is usually considered as metastatic in nature, but has also been reported to be related to other conditions, including silicon migration. The purpose of this study was to determine the rate of metastatic disease in this unique group of patients. Methods: A retrospective comparative study of 12 female patients with breast cancer with silicone implants referred for biopsy due to isolated internal mammary lymph node fluorodeoxyglucose uptake on positron emission tomography. Results: Five patients (41.6%) had histological findings related to silicone (n = 4) or non-specific inflammation (n = 1). The remaining 7 (58.3%) had histological evidence of cancer recurrence. There was no significant difference in the fluorodeoxyglucose-standardized uptake value between the two groups. Conclusions: Fluorodeoxyglucose-positive mammary lymph nodes in patients with breast cancer following silicone implant reconstruction may be due to metastatic deposits, non-specific inflammation or silicone migration. Clinical and imaging characteristics are insufficient in differentiating between these conditions. Biopsy is recommended prior to initiation of further treatment.