Superficial basaloid squamous carcinoma of the esophagus. A clinicopathological and immunohistochemical study of 12 cases.

Basaloid squamous carcinoma (BSC) is a rare variant of squamous cell carcinoma (SCC). In this study, clinicopathological and immunohistochemical characteristics of 12 superficial esophageal BSCs were examined and compared with those of typical superficial SCCs. Eight cases were classified into an elevated type, and the other four into a depressed type. High-grade intraepithelial neoplasia was not observed around the invasive lesions in five cases, and only BSC components were apparent. High-grade intraepithelial neoplasia was demonstrated in seven cases, five of which had both BSC and SCC components in the invasive lesion. A cribriform growth pattern, comedo-type necrosis, and hyaline deposits were conspicuous histological findings. CK14 was positively stained in 90% of the series, but the proportion of positive cells was small in most cases. Type IV collagen was increased or well preserved in the basement membrane in 70% of cases, but heparan sulfate was decreased in the majority. In comparison with SCCs, lymphatic permeation was observed less frequently. However, regarding the frequencies of venous permeation, nodal metastasis, p53 protein expression, and Ki-67 labeling index, no significant differences were noted. Thus, esophageal BSCs demonstrate the pathological features characteristic of an early stage, but pathological parameters related to biological behavior do not significantly vary from those typical of SCCs.