Squamous cell carcinoma arising in mature cystic teratoma of the ovary. Clinicopathologic and topographic analysis.

Clinical and pathologic features of 28 patients with squamous cell carcinoma (SCC) arising in mature cystic teratoma (MCT) of the ovary were analyzed. The overall 5-year survival rate of these patients was 52%. Clinical staging (Stage I versus Stages II or more), histologic differentiation (well versus moderately or poorly differentiated SCC), and the presence of vascular invasion were factors affecting the prognosis of these patients. In 11 tumors, including 2 of the 4 examined in stepwise serial sections, the SCC was considered to have originated from a columnar epithelium (ciliated or nonciliated) or from a metaplastic squamous epithelium. On the other hand, no SCC was a direct transition from the ordinary epidermis of the teratomatous skin tissue. These results strongly support the proposal that SCC arising in MCT derives from the columnar epithelium.