We herein report a very rare case of combined small-cell carcinoma (SmCC) of the hypopharynx, with a squamous cell carcinoma (SqCC) element. A 74-year-old man presented with a 3-month history of throat pain and hoarseness. On hypopharyngoscopy, a tumor was identified in the right anterior wall of the piriform sinus and, following examination of a biopsy sample, the lesion was diagnosed as SqCC. Total laryngectomy with bilateral neck dissection was performed and the malignancy was diagnosed as combined SmCC. One month after surgery, concomitant chemoradiotherapy with cisplatin and etoposide was administered. Immunohistochemically, the SmCC element was positive for CD56 and Ki-67 (50.2%), whereas the SqCC element was positive for cytokeratin 34βE12 and Ki-67 (47.5%). Furthermore, the SmCC element was positive for KIT and platelet-derived growth factor α (PDGFRα), while the SqCC element was positive for epidermal growth factor receptor (EGFR) and PDGFRα. By genetic analysis, a silent mutation in the PDGFRα gene was recognized. The expression of KIT, PDGFRα and EGFR in this case provided evidence that combined SmCC may be a candidate for molecular-targeted therapy, although further investigations are required.
Keywords: KIT; combined small and squamous cell carcinoma; hypopharynx; platelet-derived growth factor receptor α.