Findings:
Known cystic lesion in the right side of neck with an enhancing wall of non-uniform thickness. It shows an increase in size when compared to the previous study, currently measuring 2.5 x 5 x 3 cm, compared to 2 x 4.5 x 2.5 cm in the previous study.
Additionally, newly appreciated solid components are noted overlying the anterolateral aspect of the cyst, measuring approximately 2.2 x 2.2 cm and involving the right platysma. Surrounding fat stranding and skin thickening is noted.
Laterally, the lesion is in intimate relation to the right sternomastoid muscle, inseparable from its medial wall. Anteriorly, it is indenting the posterior surface of the right submandibular gland. Medially, it is related to the carotid sheath with compression and caliber attenuation of the right internal jugular vein. The carotid arteries are patent.
No obvious lymphadenopathy is seen.
The mandible is unremarkable without evidence of any lytic lesions.
Impacted and unerupted supernumerary tooth in the palatal side of the root tooth 2.1.
Clusters of calcifications within the lingual tonsils bilaterally, compatible with tonsilloliths. The pharynx and larynx are otherwise unremarkable.
The imaged brain and intracranial circulation are unremarkable. Hypoplastic right sigmoid sinus is noted.
Minimal mucosal thickening is seen in the maxillary sinuses bilaterally. The paranasal sinuses and the mastoid air cells are otherwise unremarkable.
The lung apices are clear.
No bony abnormality is seen. The craniocervical junction and spinal canal appear patent.
Conclusion:
Features most likely in keeping with infected second branchial cleft cyst type II on the right side. No evidence of underlying odontogenic cause. Further surveillance is advised.