An Atypical Etiology of Mediastinal Lymphadenopathy: Extraskeletal Ewing Sarcoma

Background: Ewing's sarcomas and peripheral primitive neuroectodermal tumors are high grade malignant neoplasms, arising from bone and soft tissues and are grouped in the Ewing family of tumors. Primary localization in the mediastinum is extremely rare and was treated in only a few case reports. Lymphatic localization has never been reported. We present a case of an extraskeletal Ewing sarcoma arising from lymphadenopathy in the hilar and anterior mediastinal regions with literature review. Case presentation: A 24 year old man was admitted to our institution for persistent cough, nocturnal diaphoresis, and weight loss of 6 kg. The chest X-ray displayed opacity of the left hilum at polycyclic contours. Chest Computed tomography scan confirmed supradiaphragmatic lymphadenopathy in the hilar and anterior mediastinal. Biopsy was performed. Histological and immunohistochemical analysis showed small and round cells tumor with positive staining for CD99 and vimentin, and negative staining of desmine, myogenine, actine muscle lisse, Proteine S-100, Chromogranine, CD56, pancytokeratin, myeloperoxidase and TTF1. Young age, morphological and immunohistological characters argued in favor of a tumor of Ewing group .We could not perform molecular cytogenetic analysis, because of the lack of technical structure. The staging was negative for any other metastatic disease or primitive bone tumor, and final diagnosis was primary localized Ewing sarcoma in mediastinal nodes. The patient received Ewing’s sarcoma chemotherapy regimen. Complete response was achieved after six courses. Radiotherapy was prescribed, and the same chemotherapy regimen was continued totaling a period of one year. The patient was well with no evidence of local relapse or metastasis three years after diagnosis. Conclusion: Extraskeletal Ewing sarcoma should be contemplated in the differential diagnosis of mediastinal lymphadenopathy. With multimodal treatment, the patients are potentially curable.