Ewing's sarcoma in mandibular similar to dental abscess
The patient was a 16-year-old girl who visited a dentist complaining of toothache in the summer 2010.\nWhile dealing with the tooth, a prominent lesion was detected and removed along with the tooth. The pain did not subside, and the patient returned with pain and swelling in the mandibular angle accompanied by numbness of lower lip. She was diagnosed with abscess and was admitted to the Ear, Nose and Throat (ENT) department of a hospital where the abscess was drained. Even after the drainage, the pain still persisted; therefore, part of the tissue was removed with incisional biopsy and sent to the oral and maxillofacial department at Faculty of Dentistry. It is noteworthy that bone destruction was not observed in panoramic radiography [].\nIn the horizontal and vertical computed tomography (CT) scan, a clear reduction in trabeculation with indistinct boundary was observed in the mandible posterior to the first molar region [].\nAccording to the images, the differential diagnosis of indistinct osteolitic lesions comprises histiocytosis X, Ewing's sarcoma, lymphoma, and osteomyelitis.\nThe sample contained several pieces of yellowish cream tissue, irregularly shaped with a rubbery texture. Histopathological figure has been shown colonies of proliferation of cells with dysplastic changes such as extensive cytoplasm and large nuclei, prominent small nucleolus, mitotic figures, and polymorphism in stromal connective tissue with wide areas of necrosis [].\nAccordingly, round cell tumors including Ewing's sarcoma, lymphoma (comprising anaplastic large cell lymphoma, and diffuse large cell lymphoma), metastatic carcinoma, muscular tumors (including rhabdomyosarcoma), and neuroblastoma were included in the differential diagnosis. In order to make differential diagnosis using immunohistochemical (IHC) techniques, the following indicators were assessed and results obtained were []:\nCytokeratin (CK) = -, Desmin = -, S100 = +\nLeukocyte Common Antigen (LCA) = -, Vimentin = +, CD99 = strongly +\nMetastatic carcinoma, muscular tumors, and a variety of lymphomas were ruled out due to negative CK, Desmin, and LCA, respectively. Also, due to positive CD99, neuroblastoma was ruled out too, and with strongly positive CD99 and Vimentin, the diagnosis of Ewing's sarcoma was confirmed.\nWith this diagnosis, the patient began to undergo combination chemotherapy (Vincristine, Cyclophosphmide, Adriamycin, Iphosphamide, Etoposide) to reduce lesion's size, and then she underwent mandibulectomy by an oral and maxillofacial surgeon to remove lesions. The lesion, mandibular nerve, and sub-mandibular lymph nodes were sent to the pathology department of the oral and maxillofacial department of the dentistry faculty for the final assessment.\nIn the macroscopic view, there was a piece of bone including the right half of mandible from premolar region to the end of ascending ramus containing posterior tooth and inferior alveolar nerve and sub-mandibular lymph node [].\nIn the histopathological figure, serial sections have been shown areas of bone trabecules along with normal bone marrow spaces full of hematopoietic cells, fat cells, and areas of necrosis, and hemorrhage. In addition, in slides of the medial section of lower ramus and mandibular medial angle, only a remnant of tumoral cells, including some colonies of proliferation of cells with expansive cytoplasm, unclear boundary, and large nuclei, were seen. The diagnosis of Ewing's sarcoma was established based on these and initial IHC panel, CT scan, and radiography findings. Also, nerve sample and tumor-free lymph nodes were observed []. It appears that tumor has responded to chemotherapy, and after follow-up, mandibulectomy, chemotherapy, and CT scan of the bone, systemic condition of the patient has improved.