The Pharyngolaryngeal Venous Plexus: A Potential Pitfall in Surveillance Imaging of the Neck

Abstract

Background and purpose: Among patients undergoing serial neck CTs, we have observed variability in the appearance of the pharyngolaryngeal venous plexus, which comprises the postcricoid and posterior pharyngeal venous plexuses. We hypothesize changes in plexus appearance from therapeutic neck irradiation. The purposes of this study are to describe the CT appearance of the pharyngolaryngeal venous plexus among 2 groups undergoing serial neck CTs-patients with radiation therapy-treated laryngeal cancer and patients with medically treated lymphoma-and to assess for changes in plexus appearance attributable to radiation therapy.

Materials and methods: For this retrospective study of 98 patients (49 in each group), 448 contrast-enhanced neck CTs (222 laryngeal cancer; 226 lymphoma) were assessed. When visible, the plexus anteroposterior diameter was measured, and morphology was categorized.

Results: At least 1 plexus component was identified in 36/49 patients with laryngeal cancer and 37/49 patients with lymphoma. There were no statistically significant differences in plexus visibility between the 2 groups. Median anteroposterior diameter was 2.1 mm for the postcricoid venous plexus and 1.6 mm for the posterior pharyngeal venous plexus. The most common morphology was "bilobed" for the postcricoid venous plexus and "linear" for the posterior pharyngeal venous plexus. The pharyngolaryngeal venous plexus and its components were commonly identifiable only on follow-up imaging.

Conclusions: Head and neck radiologists should be familiar with the typical location and variable appearance of the pharyngolaryngeal plexus components so as not to mistake them for neoplasm. Observed variability in plexus appearance is not attributable to radiation therapy.

FIG 1.

Transverse histopathologic section of the hypopharynx of a full-term fetus at the level of the cricoid cartilage shows the locations of the PCVP and the PPVP. Reproduced from Butler with permission from BMJ Publishing Group Ltd.

FIG 2.

Labeled (A) and unlabeled (B) axial neck CT images with contrast at the level of the cricoarytenoid joints in a patient without visible PLVP demonstrate the expected locations of the PCVP (asterisk, A) between the larynx anteriorly and the hypopharyngeal mucosa (dashed line, A) posteriorly, and the PPVP (pound sign, A) between the hypopharyngeal mucosa anteriorly and the inferior constrictor musculature (solid line, A) posteriorly. Axial neck CT images with contrast in 2 additional patients (C and D) demonstrate visible PCVP (arrows, C) and visible PPVP (arrows, D).

FIG 3.

Axial contrast-enhanced neck CT images obtained before (A and C) and after (B and D) definitive radiation therapy for laryngeal squamous cell carcinoma (arrow, A). Posttreatment images demonstrate a substantial decrease in size of the treated tumor (arrow, B) as well as prominent PCVP (circle, D) that was not definitively identifiable on the baseline pretreatment neck CT (circle, C). The prominent PCVP (circle, D) was described as suspicious for progressive neoplasm but confirmed to be vascular after 22 months of imaging follow-up.

FIG 4.

Axial contrast-enhanced neck CT images obtained in 3 different patients demonstrate representative images of the PCVP (arrows, A–C) at the cricoid cartilage level (A), the arytenoid cartilage level (B), and the supra-arytenoid level (C).

FIG 5.

Axial contrast-enhanced neck CT images in 3 different patients demonstrate representative examples of bilobed (arrows, A), dot-dash (arrows, B), and linear (arrows, C) PCVP morphology.

FIG 6.

Axial contrast-enhanced neck CT images in 3 different patients demonstrate representative examples of linear (arrows, A), dot-dash (arrows, B), and bilobed (arrows, C) PPVP morphology.