ABSTRACT
Postirradiation extraosseous osteogenic sarcomas are uncommon in the head and neck, despite the extensive use of high-dose radiation. It has been described as de novo radiation-induced neoplasm. We present a 73-year-old male who had been treated by radiotherapy for gingival cancer 7 years earlier and later developed extraosseous osteogenic sarcomas (EOSs) of the neck. Microscopically, the neck mass was composed with mesenchymal malignant cells with cartilaginous and osteogenic differentiation. Immunohistochemical stain demonstrated strong positivity of tumor cells for Snail, the one of major epithelial-mesenchymal transition (EMT) inducer. The E-cadherin expression was scarce, showing inverse relationship to Snail expression. Compared with previous squamous cell carcinoma (SCC) of the gingiva, the present EOS sample revealed the remained epithelial cells on cytokeratin immunohistochemistry, suggesting the tumor arise from the cells of epithelial origin. We have also reviewed the previous 6 cases of head and neck EOSs carefully. The clinicopathologic features of the unusual lesion suggest that it is an incomplete EMT of precedent epithelial malignancy rather than de novo pathology.