Can avid lymph nodes be as a result of inflammation not cancer

Yes, avid lymph nodes can absolutely be caused by inflammation, not cancer.

Inflammation is a well-documented cause of PET avidity. A 2011 study of mediastinal lymph nodes found benign granulomatous disease like tuberculosis and sarcoidosis showed SUVmax values up to 11.8, overlapping with malignant lymphoma [2]. The same study showed that at the standard SUVmax cutoff of 2.5, specificity was only 40%, meaning 6 in 10 benign nodes would be falsely flagged as suspicious [2]. Even at a higher cutoff of 6.2, specificity only reached 70% [2].

Sarcoidosis is a classic mimic. A 2018 case report documented FDG-avid mediastinal, hilar, and supraclavicular lymph nodes that biopsy confirmed as noncaseating granulomatous sarcoidosis in a cancer patient [3]. A 2015 study found that among 65 benign lung nodules removed surgically, 57% were granulomatous disease and 42% were active infections [1]. PET avidity was present in 62% of those benign nodules [1].

The retrieved evidence focuses on FDG-PET, not PSMA-PET specifically. That is a real gap. But the mechanism is the same: activated immune cells consume glucose and express surface markers that tracers bind. Inflammation is not a rare exception; it is a common cause of false-positive lymph node findings.

My call: avid lymph nodes from inflammation are a documented, common possibility, not a remote one. The SUV number alone cannot reliably separate them from cancer. Biopsy or follow-up imaging is the only way to know. Confidence: moderate, limited by the absence of PSMA-specific false-positive data in this retrieval.