Isolated Cystic Neck Mass as Only Presentation of Tonsillar Carcinoma.

Isolated cystic cervical swelling may be a presentation of a branchial cyst, tubercular lymphadenitis, or maybe a metastatic lymphadenopathy from different head and neck subsites like pharynx and thyroid, etc. The location or level of swelling may give hints towards the primary pathology from where it spreads. Aspiration cytology and radiology sometimes fail to confirm its malignant nature and the primary site of origin. In these scenarios, 18- FDG PET plays an essential role in diagnosing these cases. A 38-year-old otherwise asymptomatic male patient presented with slowly growing right neck swelling for five months duration. Clinical, radiology, and cytopathological evaluation suggested a cystic neck node but didn't confirm the diagnosis. The oral cavity, oropharynx examination, laryngoscopy and hypo-pharyngoscopy evaluation were grossly normal. On suspicion, 18-FDG PET was done, which showed increased uptake in the right tonsil and solid cystic lesion in the right level II and III cervical regions. With a provisional diagnosis of suspected carcinoma of the right tonsil with ipsilateral metastatic lymphadenopathy, bilateral tonsillectomy with right-side modified radical neck dissection was done. The diagnosis was confirmed as HPV-related oropharyngeal squamous cell carcinoma right side with cervical nodal metastasis and was treated with adjuvant postoperative chemoradiotherapy. Now, the patient is asymptomatic at thirty-six months of follow-up.