Importance of mediastinal granulomatous/sarcoid-like lymphadenopathy in extrathoracic malignancies.

Background: In patients with extrathoracic malignancies (ETM), granulomatous lymph adenopathy called sarcoid-like reactions (SLR) can be seen in the regional or draining lymph nodes. We hypothesized that SLR may be a sign of imminent metastasis and investigated the clinical course and rate of recurrence in patients with ETM and granulomatous mediastinal lymphadenopathy (MLN).

Methods: In this retrospective observational study, we reviewed the medical files of patients with known ETM and who underwent EBUS-TBNA for initial staging or detection of recurrence from 2011 to 2023. Patients with granulomatous MLN were included.

Results: Forty-one patients (29 female) enrolled in the study. Breast and colorectal carcinomas were the most common malignancies. A total of 81 lymph nodes were sampled. The final diagnosis of patients was five sarcoidosis, one tuberculosis, one second primary, one drug reaction, and 33 SLR. Among patients with SLR, in one patient lymph nodes progressed during the follow-up and were accepted as false-negative without confirmatory biopsy. The negative predictive value (NPV) of granulomatous MLN for metastasis was 97.05%.

Conclusion: Granulomatous MLN may be due to tuberculosis, drug reaction, sarcoidosis, or SLR in patients with ETM. SLR has a high NPV in patients with ETM. Follow-up imaging rather than confirmatory biopsy is reasonable in these patients.