Sarcoidosis Mimicking Mediastinal Lymph Node Metastases of Cervix Carcinoma: An Unusual Association

Sarcoidosis has been reported to occur in patients preceding, concurrent with, or after the diagnosis of cancer.[] A causal relationship between sarcoidosis and the onset of several hematologic malignancies and solid tumors appears to exist; specifically, these include tumors that affect the liver, lung, skin, testicles, and cervix.[] This association has been well described, but the matter remains controversial: whether this association is just a coincidence or the consequence of a pathogenic mechanism, even if the last hypothesis is the most likely and the association might be non-fortuitous, as suggested by some reports which tried to connect cancer and sarcoidosis.[] Several mechanisms have been proposed to explain the relationship between sarcoidosis and cancer. These include chronic inflammation, immune dysfunction, shared etiologic agents, and genetic susceptibility to both cancer and autoimmune diseases.[] In addition, sarcoidosis might be a side effect of the chemotherapeutic treatments as it has been reported in hematologic malignancies. Especially alpha interferon, which is considerate, the most common postulated causative agent, although many other agents such as cisplatin, IL-2 for solid tumors have also been reported.[] Therefore, a concentrated effort on prospective studies would be required to address this issue.

FDG-PET/CT has many proven applications beyond cancer imaging; its superior anatomic localization of increased metabolic activity has been found to be more sensitive for inflammatory or infectious processes such as sarcoidosis than other nuclear imaging techniques such as 67Ga imaging.[] Nevertheless; it has to be considered that PET/CT can lead to false-positive results in cases of infection and inflammation where glucose consumption is prevalent. Therefore, preoperative staging for a malignant tumor is sometimes difficult when swelling and intense FDG uptake in lymph nodes is observed.[] Chundru et al.[] proposed some criteria based on case reviews to distinguish sarcoidosis from malignancy on FDG-PET/CT: sarcoidosis typically demonstrates higher activity in the central mediastinal nodes than in the hilar and lobar nodes, affects both sides of the mediastinum symmetrically, not follows any specific lymph node drainage, and often does not present with a parenchymal lung lesion.

On our patient, the FDG-PET/CT scan revealed in addition to the known hypermetabolic tumor of the cervix FDG, avid mediastinal and hilar lymphadenopathies, with no other FDG uptake on the rest of the body, especially on pelvic lymph nodes. This "bypass" of lymphatic nodes of the abdomen and pelvis, and the absence of disseminated disease, drew our intention on a possible association of an inflammatory disease with the uterine tumor, mediastinoscopy was performed and histopathologic findings corroborate the diagnosis of sarcoidosis. Regardless of cancer prognosis and fortunately, the prognosis for sarcoidosis is favorable following glucocorticoid therapy, and the symptoms often resolve themselves spontaneously.[]