Sarcoidosis of mediastinal lymph nodes mimicking distant metastasis of oral squamous cell carcinoma : a case report and review of literature

Sarcoidosis is a systemic, chronic inflammatory disease with unknown cause and is characterized by formation of epithelioid granulomas in various organs, mainly the lungs and lymphatic system as mediastinal lymph nodes (LNs). Lymphadenopathy is common in sarcoidosis. Subsequent cancer also tends to occur in patients with the disease, and the most frequent is lymphoma and cancer of the lung. Head and neck cancer is uncommon but possible. We report a 70-year-old woman with squamous cell carcinoma (SCC) of the mandibular gingiva concomitant with mediastinal multiple lymphadenopathy, and a medical history of chronic sarcoidosis. Mediastinal LNs showed increased uptake of 2-[18F]-fluoro-2-deoxy-d-glucose (FDG) with positron emission tomography (PET). Subsequent to lymphadenectomy, the histological diagnosis was lymphadenopathy caused by sarcoidosis. Next, we performed wide local excision of the gingival tumor. During follow-up, a pulmonary lesion was detected by computed tomography at 3 years and 11 months after surgery, and diagnosed as pulmonary sarcoidosis, which had been stable without treatment until now. After follow-up of 5 years, the patient was alive without signs of local recurrence or metastasis. The combination of oral SCC and sarcoidosis of the mediastinal LNs in a sarcoidosis patient has not been previously reported. FDG-PET was not able to distinguish LN metastasis from lymphadenopathy caused by sarcoidosis. In our case, her chronic inflammatory condition with sarcoidosis as well as ill-fitting dentures could have increased the risk of oral cancer. We suggest that clinicians should carefully check for the development of subsequent oral cancer in patients with a past history of sarcoidosis. To avoid inaccurate staging and incorrect therapy, LN biopsy should be promptly performed following a diagnosis of cancer and multiple lymphadenopathies in patients with a history of sarcoidosis. Lymphadenopathy with sarcoidosis patients have malignant potential, especially those who develop subsequent cancer. Misdiagnosis of LN malignancy and sarcoidosis may lead to unnecessary adjuvant therapy or worse prognosis.