Sarcoidosis or sarcoid-like reaction with mediastinal lymphadenopathy in patients after breast cancer surgery.

[BACKGROUND] Patients with breast cancer present with lymphadenopathy involving non-caseating epithelioid cell granulomas in the mediastinum or axilla, referred to as sarcoidosis or sarcoid-like reactions (SLRs). However, sarcoidosis/SLRs prevalence and clinical presentation remain unclear. This study aimed to determine the frequency and clinical presentation of sarcoidosis/SLRs among postoperative patients with breast cancer.

[METHODS] Among all patients who underwent surgery for early-stage breast cancer at St. Luke's International Hospital in Japan between 2010 and 2021, those who subsequently developed enlarged mediastinal lymph nodes and underwent bronchoscopy for suspected breast cancer recurrence were included. Patients were classified into sarcoidosis/SLR or metastatic breast cancer groups, and the clinical characteristics were compared.

[RESULTS] A total of 9,559 patients underwent breast cancer surgery; bronchoscopy was performed to diagnose enlarged mediastinal lymph nodes in 29 cases. Breast cancer recurrence was observed in 20 patients. Eight women with a median age of 49 years (range 38-75) and a median time from surgery to diagnosis of 4.0 years (range 0.2-10.8) were diagnosed with sarcoidosis/SLRs. Four of the eight patients underwent mammoplasty with silicone breast implants (SBIs), and two experienced postoperative recurrences of breast cancer before or after lymphadenopathy, which was considered inciting factors for SLRs. The remaining two cases could have developed sarcoidosis after breast cancer surgery with no underlying causes for SLR.

[CONCLUSIONS] Postoperative sarcoidosis/SLRs rarely occur in patients with breast cancer. An adjuvant action of SBI likely contributed to the progression of SLRs; few cases exhibited a causal relationship with breast cancer recurrence.