FDG-PET/CT of sarcoidosis and sarcoid reactions following antineoplastic treatment

Abstract

Sarcoidosis or sarcoid reactions, which appear as FDG-avid lesions in oncologic patients, need to be differentiated from disseminated malignancies. We aimed to promote awareness of development of sarcoidosis or sarcoid reactions after antineoplastic therapy to avoid diagnostic errors with FDG-PET/CT findings and assess the utility of FDG-PET/CT for follow-up. We retrospectively reviewed radiological reports of FDG-PET/CT scans performed between January 2009 and December 2011. Among oncologic patients with more than 2 FDG-PET/CT scans, those with nearly symmetrical increases in FDG uptake in the hilar or mediastinal lymph nodes were identified, and those with known sarcoidosis, concurrent diagnoses of sarcoidosis with malignancy, or histopathologically proven malignancies were excluded. Then, only those cases were selected for which sarcoidosis or sarcoid reactions were diagnosed. Four of 376 oncologic cases met the criteria. At 9 months to 6 years after antineoplastic therapy, abnormal FDG uptakes were observed in the hilar, mediastinal, abdominal, pelvic, and inguinal nodes, and/or spleen and lung parenchyma with SUVmax up to 17.7. On the basis of these findings, 1 patient received anticancer chemotherapy because of tumor recurrence suspicion. A gradual decrease in FDG uptake was observed on subsequent PET/CT scans. Sarcoidosis or sarcoid reactions should be considered in differential diagnosis of oncologic patients who have developed FDG-avid lesions any time after antineoplastic therapy. FDG-PET/CT can be used for follow-up in nondiagnostic situations to detect decreases in FDG uptake due to presence of sarcoidal granulomas.

Sarcoid Like Reaction Following Adjuvant Chemotherapy of Breast Cancer

“…The use of FDG-PET in the management of malignancy is widely recognized and its use has been increasing in recent years. Sarcoid-like reaction is a wellknown benign cause of FDG uptake in cancer patients and needs to be differentiated from active nodal metastatic disease [5]. In this report, we describe a case in which a woman with breast cancer developed sarcoidlike reaction following chemotherapy.…”

Can a Sarcoid-like Reaction Induced by a T-cell Mediated Immune Response Mimic Breast Cancer Metastasis?

“…Sarkoidozun genetik olarak duyarlı kişilerde spesifik ajanlara maruziyet sonucu gelişen, T hücre aracılı immün yanıt sonucu ortaya çıktığı düşünülmektedir. Bu bağlamda, sarkoid reaksiyonların tümöral tutulumu olan hastalarda; doğrudan tümör hücrelerinden köken alan veya antineoplastik tedavinin etkisiyle salınan bir takım antijenlerin tetiklemesiyle gelişebileceği düşünülmektedir (12). Nitekim bazı olgularda tedavi sırasında da sarkoid reaksiyonlar gelişmiştir.…”

How are cancer and connective tissue diseases related to sarcoidosis?

“…The clinician must not fail to diagnose the associated underlying malignancy that would delay the necessary therapy. These granulomatous reactions may be PET positive, and, therefore, PET positivity is unreliable as surrogate of relapse or spread of otherwise controlled malignancies [64][65][66][67]78,79]. Although the necessity of two organs demonstrating granulomatous inflammation in order for sarcoidosis to be diagnosed has recently been debated [11], it would be useful criteria to distinguish these two entities.…”