Imaging Findings
The patient suffered from dyphagia since a few weeks. Indirect laryngoscopy revealed mucosal abnormalities in the right pyriform sinus, suspect for a malignant lesion The patient was referred for a CT study of the neck. This study showed the presence of a relatively low-volume soft tissue mass in the right pyriform sinus, extending beneath the mucosa into the retrocricoid area, and invading the larynx. There was no evidence for extrapharyngeal spread, nor neck adenopathies.
A biopsy revealed squamous cell carcinoma. Considering the radiological findings, the patient was treated with radiotherapy. One year after treatment, there is no evidence for residual or recurrent disease.
Discussion
The hypopharynx lies behind the larynx; it is subdivided in three subsites: the paired pyriform sinuses, the posterior hypopharyngeal wall, and the postcricoid region. The majority of malignant hypopharyngeal tumors are squamous cell carcinoma. Cigarette smoking and alcohol abuse are major risk factors. The characteristic symptoms are sore throat, referred otalgia and dysphagia, but a neck mass (due to metastatic neck adenopathies) may be the presenting symptom.
Endoscopically, the extent of hypopharyngeal cancer is often underestimated because of submucosal tumor spread. Such submucosal spread can be visualized by CT or MRI.
Cancer of the posterior hypopharyngeal wall commonly appears as a flat but often widespread mass lesion, and may spread to the oropharynx; these cancers may also invade the prevertebral muscles.
Pyriform sinus cancers have the tendency to grow anteriorly in the laryngeal paraglottic space. Anterolateral spread may result in invasion of the thyroid cartilage. Lateral extension may result in extrapharyngeal spread in the neck; the large neck vessels are then at risk of becoming involved by the primary tumor.
As in this case, inferior extension into the postcricoid area may occur submucosally and therefore endoscopically undetectable.
Cancer originating in the postcricoid area is rare. Involvement of the proximal esophagus by hypopharyngeal cancer is rarely seen.
Neck lymphadenopathy is often present in hypopharyngeal cancer.
The treatment depends on the location, extension pattern and volume of the lesion. Most posterior hypopharyngeal wall lesions are treated by radiotherapy. Postcricoid cancer is treated by total laryngopharyngectomy. If the tumor extends to the esophagus, an esophagectomy is also required. In cancer confined to the pyriform sinus or with minimal extension beyond it, partial laryngopharyngectomy is feasible if the pyriform apex is not involved; this may leave the patient with a functional larynx. If the apex is involved, the risk of laryngeal invasion is considered too high and total laryngopharyngectomy has to be performed.
Low volume hypopharyngeal cancer can be effectively treated by radiotherapy. CT (or MRI) is helpful in selecting patients into a favorable group for radiation treatment, by providing an estimation of tumor volume.
Differential Diagnosis List
Squamous cell carcinoma of the pyriform sinus
Final Diagnosis
Squamous cell carcinoma of the pyriform sinus
