BASALOID-SQUAMOUS CELL-CARCINOMA OF THE ESOPHAGUS - DIAGNOSIS AND PROGNOSIS

BACKGROUND. Basaloid squamous cell carcinoma (BSCC) is a recently reco gnized, poorly differentiated variant of squamous cell carcinoma (SCC) , which is located predominantly in the upper aerodigestive tract. MET HODS. In this study, clinical and pathologic parameters of 17 BSCCs an d 133 typical SCCs of the esophagus that underwent potentially curativ e resection (no distant metastases, no residual tumor) were compared. In addition, light microscopic, electron microscopic, and immunohistoc hemical features of BSCC were investigated, to determine whether this type of carcinoma could be differentiated from other poorly differenti ated carcinomas of the esophagus. RESULTS. Light microscopic study sho wed that BSCC was composed of relatively small tumor cells, arranged i n solid lobules with abundant comedo-type necrosis. BSCC was almost in variably accompanied by areas of concomitant typical SCC, foci of squa mous cell differentiation, and/or severe squamous cell dysplasia or ca rcinoma in situ of the adjacent mucosa. Ultrastructurally, BSCC incons istently showed features of squamous cell differentiation. Immunohisto chemically, BSCC displayed poor reactivity for antibodies against wide -range cytokeratins and cytokeratin subtypes that are typical of squam ous cell epithelia (cytokeratin 13 and cytokeratin 14). Infrequently, expression of Leu7, smooth muscle actin, and S-100 protein was found. In comparison with typical SCC, the characteristic features of BSCC we re older patient age, higher proliferative activity (MIB-1 labelling i ndex), and higher apoptotic indices. No differences were found with re gard to pT classification, pN classification, tumor size, blood vessel invasion, lymphatic vessel invasion, neural invasion, or patient gend er. Moreover, no differences in overall survival rates were found. CON CLUSIONS, BSCC is a distinct histopathologic variant of SCC, character ized by a poor degree of differentiation and high proliferative activi ty. However, after potentially curative resection, the prognosis of pa tients with BSCC of the esophagus does not differ from that of patient s with typical SCC. (C) 1997 American Cancer Society.