SASS Clinical Note #2
Hypopharynx, by definition, begins superiorly at the level of the valleculae and extends inferiorly to the UES. Hypopharyngeal cancers commonly present as nodal metastases; that is, cancer that has spread from the lymph nodes in the neck.
Piriform Sinus Tumors
These account for 70% of cancers originating in the hypopharynx. Tumors originating from the medial wall of the piriform sinus behave similarly to supraglottic tumors arising from the aryepiglottic folds. Posteriorly, there is little to impede tumor extension into the postcricoid space or crossing from the ipsilateral arytenoid to the contralateral arytenoid. Lateral wall tumors also have few barriers to tumor growth.
Hypopharyngeal Wall Tumors
These tumors are less common, unusual to see a lesion confined to and clearing originating from the lateral or posterior wall. They can spread through the walls posteriorly or laterally into the oropharynx walls. Posterior wall tumors can invade prevertebral tissues or invade even more deeply to the bones of the cervical spine.
Least common hypopharyngeal tumors. If found, they are usually in advanced stages. They can extend into the lateral channels or directly into laryngeal structures.
Taken from: Gunderson, L & Tepper, J. (2011). Clinical Radiation Oncology (3rd Ed.) Saunders