Primary composite tumour with bipartite differentiation of the esophagus

Primary small cell carcinoma of the esophagus is a rare tumour. A primary c omposite tumour of the esophagus is even rarer and only four cases had been reported in the literature up to August 1998. The definitive histogenesis of this tumour remains controversial in spite of the,additional information provided by electron microscopy and immunohistochemistry. In the presented :case, histologically, the tumour tissue was composed of two malignant comp onents: approximately 50 % of a moderately differentiated squamous cell car cinoma, and approximately 50 % of a small cell carcinoma. A lot of morpholo gical transition zones were observed between the squamous cell carcinoma co mponents and the small cell carcinoma components in some areas in the squam ous cell carcinoma component. Histochemically and immunohistochemically, th e small cell carcinoma cells demonstrated argyrophil granules, and Cytokera tin and Chromogranin A reactivity, but the squamous cell carcinoma cells de monstrated only Cytokeratin reactivity. Negative reactivity for argentaffin granules, neuron-specific enolase and S-100 were observed in both the smal l cell carcinoma and the,squamous cell carcinoma components. Histological, histochemical:and immunohistochemical findings suggest that a primary compo site tumour of the esophagus may be derived from a totipotent primitive cel l in the basal region of the squamous mucosa of the esophagus. The patient received chemotherapy preoperatively but died one month after the initial d iagnosis.