Sarcoid-like reaction mimicking vaginal cancer recurrence

A sarcoid-like reaction is a development of non-caseating granuloma in patients with underlying malignancy and represents a false positive finding on positron emission tomography/computed tomography (PET/CT). A sarcoid-like reaction is a benign condition; therefore, differentiating a sarcoid-like reaction from cancer recurrence is necessary. Only uterine and ovarian cancer related cases have been reported in the gynecological field and to the best of our knowledge, this is the first case of a sarcoid-like reaction in vaginal cancer. A 59-year-old vaginal cancer patient received concurrent chemoradiotherapy and achieved complete remission. Recurrence of vaginal cancer was suspected because of the elevation of serum squamous cell carcinoma antigen level. PET/CT revealed abnormal uptake at the bilateral mediastinal and hilar lymph nodes. A non-caseating granuloma was detected from the biopsy of the swollen lymph nodes. No evidence of cancer recurrence was observed. A sarcoid-like reaction should be considered when evaluating PET/CT in cancer patients to prevent unnecessary treatments.