Transitional (cylindric) cell carcinoma with endodermal sinus tumor-like features of the nasopharynx and paranasal sinuses. Clinicopathologic and immunohistochemical study of two cases.

We report two cases of adult patients with primary tumors in the nasopharynx and paranasal sinuses, which were characterized histologically by areas of transitional cell (cylindric or "schneiderian") carcinoma and other foci virtually indistinguishable from endodermal sinus tumor (yolk sac carcinoma). Immunohistochemical studies supported the impression of yolk sac differentiation. Both patients were treated with irradiation and multidrug chemotherapy. One patient died of uncontrollable recurrence of tumor, whereas the other developed locally recurrent, transitional cell carcinoma in the absence of yolk sac tumor. The concurrence of these patterns of carcinoma, which has been undescribed previously to the best of our knowledge, seems to be associated with more aggressive biologic behavior than pure transitional cell carcinomas of this region.