A CASE OF BASALOID-SQUAMOUS CARCINOMA OF THE ESOPHAGUS - IMMUNOHISTOCHEMICAL AND ULTRASTRUCTURAL STUDIES

A case of basaloid-squamous carcinoma of the esophagus in an 83 year o ld man is reported. The esophageal tumor showed a fungating growth at the junction of the middle and lower esophagus and was composed micros copically of submucosal multiple nests with solid and cribriform-like patterns accompanied with a small focus of squamous cell carcinoma adj acent to the overlying esophageal epithelium. The structural features closely resembled those of basaloid-squamous carcinoma. The submucosal tumor cells were immunohistochemically positive for epithelial membra ne antigen, wide spectral keratin, alpha actin and S-100 protein. By e lectron microscopy, the tumor cells had microvilli, desmosomes and bun dles of myofilaments, and replicated basement membranes were frequentl y observed adjacent to the nests. The positive immunoreaction of S-100 protein and alpha actin and the existence of bundles of myofilaments indicated that the present tumor did not correspond well with basaloid -squamous carcinoma. In addition, there was no evidence of true glandu lar lumina in the tumor nests, a finding which was inconsistent with t hat of adenoid cystic carcinoma. From the immunoreactivity of S-100 pr otein and ultrastructural features, it was considered that the present submucosal tumor had originated from undifferentiated pluripotential primitive cells, which differentiated to myoepithelial cells.