Role of Whole body PET/CT and Examination under anesthesia with multi-site biopsy in evaluating CUP

Anupam Kanodia; Chirom Amit Singh; Pirabu Sakthivel; Shamim Ahmad Shamim; Kapil Sikka; Rajeev Kumar; Aanchal Kakkar; Rakesh Kumar; Siddhartha Datta Gupta; Ashu Seith Bhalla; Alok Thakar; Suresh C Sharma

doi:10.1007/s12070-020-02268-z

Role of Whole body PET/CT and Examination under anesthesia with multi-site biopsy in evaluating CUP

Indian J Otolaryngol Head Neck Surg. 2022 Oct;74(Suppl 2):2656-2662. doi: 10.1007/s12070-020-02268-z. Epub 2021 Jan 13.

Affiliations

¹ Department of Otorhinolaryngology and Head-Neck Surgery, All India Institute of Medical Sciences, Ansari Nagar, New Delhi India.
² Department of Nuclear Medicine, All India Institute of Medical Sciences, Ansari Nagar, New Delhi India.
³ Department of Pathology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi India.
⁴ Department of Radiology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi India.

Abstract

To evaluate the role of 18FDG-WBPET-CT, Examination under anesthesia (EUA), and multiple-site biopsy in detecting the occult site in head & neck carcinoma of unknown primary (HN-CUP). In this prospective study, 22 patients with diagnosed CUP, after a thorough outpatient endoscopic evaluation of upper airway and radiological evaluation (CT/MRI) that ruled out a primary lesion were included. These patients subsequently underwent whole-body PET-CT and EUA. Based on the presence of suspicious findings ( +) or their absence (-) on 18FDG-WBPET-CT (P) and EUA (E), we divided the patients into 5 groups: P-E-, P-E + , P + E-, P + E + , and P + or E + . All these patients underwent bilateral palatine tonsillectomy, bilateral nasopharyngeal biopsy, and ipsilateral lingual tonsillectomy for identification of occult primary. Out of 22 patients, the primary could be detected in 4 patients (18%) after the workup (three in the oropharynx and one in the hypopharynx, all ipsilateral). 18FDG-PET-CT suspected primaries in 7 patients; biopsy was positive for three (sensitivity-75%, specificity-77%, PPV-43%, NPV-93%). Out of 5 patients, who had suspicious findings on EUA, 3 of the biopsies revealed malignancy (sensitivity-75%, specificity-88%, PPV-60%, NPV-94%). Both PET-CT and EUA when combined, yield a NPV of 100% if both are negative and PPV of 100% when both are positive for suspicious findings. No primary was identified in the absence of a suspicion by PET-CT or EUA. Without a suspicion on 18FDG-WBPET-CT and EUA, there is a limited role of multiple-site biopsies in patients of HN-CUP.

Keywords: Carcinoma of unknown primary; Metastatic cervical lymphadenopathy; Occult primary of head and neck; Positron emission tomography; Tonsillectomy.