Objective Carcinosarcoma consists of carcinomatous and sarcomatous tissues and is an aggressive malignant tumor. It is rarely reported in the hypopharynx. Methods A 72-year-old man presented with dysphagia and dyspnea. Laryngoscopy, computed tomography (CT), and 18F-fluorodeoxyglucose positron emission tomography/CT (18F-FDG PET/CT) showed a neoplasm on the left posterior hypopharyngeal wall. The patient underwent bilateral neck dissection and excision of the hypopharyngeal cancer followed by postoperative radiation therapy. Results Immunohistochemistry revealed carcinomatous cells with membrane positivity for cytokeratin, glucose transporter-1 (GLUT-1), phosphoinositide-3 kinase (PI3K), hypoxia-inducible factor-1α (HIF-1α), and hexokinase-II as well as sarcomatous cells with membrane positivity for smooth muscle actin, GLUT-1, HIF-1α, and PI3K. Histopathology and immunohistochemistry revealed a true carcinosarcoma of the hypopharynx (pT3N0M0, Stage III). Conclusions Thorough immunohistochemistry is required for a correct diagnosis of hypopharyngeal carcinosarcoma. 18F-FDG PET/CT may help to distinguish hypopharyngeal carcinosarcoma from benign tumors.
Keywords: 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT); Hypopharyngeal carcinosarcoma; glucose transporter-1 (GLUT-1); hexokinase-II (HK-II); histopathology; immunohistochemistry.