(9) Individual tumor cells are often round to oval with scant or moderate eosinophillic cytoplasm and pleomorphic nuclei with rhabdoid and epitheloid cells scattered at periphery.9 ESMC expresses neuroendocrine differentiation with strong immunopositivity for vimentin and synaptophysin (7) and weak or focal positivity for EMA and S-100.7 Myxoid matrix with lobulated neoplastic cells is also seen in chordoma, parachordoma, chordoid meningiomas, and myxopapillary ependymoma.
(1) Primary nasopharyngeal ESMC can often be misdiagnosed with squamous cell carcinoma nasopharynx, melanomas, lymphomas, soft tissue sarcomas, Ewing sarcoma, skeletal chondrosarcomas, chordomas, parachordomas, myoepithelial carcinoma, myxopapillary ependymomas, chordoid meningiomas, and myxoid liposarcoma.
Several differential diagnoses should be excluded, such as myxoid chondrosarcoma, myxoid liposarcoma, and
parachordoma [10], but the presence of physaliphorous cells and the peculiar immunohistochemical features, for example, positivity for cytokeratins, vimentin, epithelial membrane antigen (EMA), and S-100 protein, can be helpful for achieving the correct one.