Primary combined adenoid cystic carcinoma, basaloid squamous cell carcinoma, and squamous cell carcinoma of the esophagus.

basaloid squamous cell carcinoma of the esophagus are rare [1–4], while esophageal combined carcinoma is very rare [5]. Most cases of combined carcinoma of the esophagus consist of squamous cell carcinoma, adenocarcinoma, and small cell carcinoma [5]. This is the first report of combined adenoid cystic carcinoma, basaloid squamous cell carcinoma, and squamous cell carcinoma of the esophagus. A 48-year-old man was admitted because of dysphagia. Endoscopy revealed a tumor in the esophagus and biopsy samples showed adenoid cystic carcinoma and squamous cell carcinoma. The esophagus was resected and the resected specimen contained a raised tumor measuring 3 × 2 × 1 cm (●" Fig. 1). Microscopically the tumor was composed of adenoid cystic carcinoma (proportion of tumor: 30%;●" Fig. 2a), basaloid squamous cell carcinoma (proportion of tumor: 40%; ●" Fig. 2b), and keratinizing squamous cell carcinoma (proportion of tumor: 30%;●" Fig. 2c). An immunohistochemical study using the Dako Envision method, as previously reported [6], was carried out (●" Table 1). Positive findings characteristic of the adenoid cystic carcinoma component included presence of mucins, p63, CD10, KIT, platelet-derived growth factor-α (PDGFRA), CA19–9, and MUC1, those characteristic of the basaloid squamous cell carcinoma component included presence of p63, p53, PDGFRA (●" Fig. 2d), CEA, and CA19–9, and those characteristic of the squamous cell carcinoma component included presence of p63, p53, EMA, and MUC1. Adenoid cystic carcinoma of esophagus is thought to arise from esophageal glands, basaloid squamous cell carcinoma from transdifferentiation of squamous cell carcinoma, and squamous cell carcinoma from the surface squamous epithelium. I believe that in the present case, the adenoid cystic carcinoma and basaloid squamous cell carcinoma components of the tumor were derived from the squamous cell carcinoma, as suggested by the immunohistochemical study. The squamous cell carcinoma component showed glandular differentiation and expression of MUC1, which is unusual, indicating the presence of the apomucin gene in this component of the tumor. The expression of PDGFRA and CA19–9 in the basaloid squamous cell carcinoma was also unusual, and it might have represented transformation of this component into adenoid cystic carcinoma. The adenoid cystic carcinoma component showed typical immunohistochemical features of this tumor. Primary combined adenoid cystic carcinoma, basaloid squamous cell carcinoma, and squamous cell carcinoma of the esophagus