Sarcoidosis as a benign cause of lymphadenopathy in cancer patients.

Background: Cancer and sarcoidosis have been associated in several small case series. This association makes the cancer patient with lymphadenopathy a diagnostic dilemma: malignant involvement of the lymph nodes is common, but benign diagnoses are possible and must be considered.

Methods: We conducted a retrospective chart review of all patients with a diagnosis of sarcoidosis or mediastinal adenopathy who underwent mediastinoscopy at the Swedish Medical Center and Cancer Institute from 2004 to 2008.

Results: Five hundred sixty-five mediastinoscopies were performed. There were 41 cases of biopsy-proven sarcoidosis. Twenty-one cases of sarcoidosis were diagnosed after a diagnosis of cancer. No primary cancer type was predominant. Cancers were of all stages, with and without lymph node involvement. The most common positron emission tomography combined with a computed tomography scan (PET CT) finding was bilateral hilar adenopathy with symmetric standardized uptake values (SUV) in the 4 to 15 range (62%), but many other PET CT patterns were present.

Conclusions: Hypermetabolic lymphadenopathy on staging or surveillance imaging presents a diagnostic dilemma. Sarcoidosis must be considered in the differential diagnosis of patients with a history of malignancy who develop lymphadenopathy. It is imperative to obtain a tissue diagnosis before instituting therapy for presumed cancer recurrence.