Diagnostic accuracy and safety of fine‐needle aspiration biopsy of the parapharyngeal space

Abstract

Fine-needle aspiration (FNA) biopsy of the parapharyngeal space (PPS) is a diagnostic challenge and sampling is often done without image guidance, often trans-orally. Primary PPS tumors are rare, and there is a broad differential diagnosis. The accuracy of PPS FNA, in particular without CT-guidance and using liquid-based cytology (LBC), has not been well studied. Pathology records from our institution (a 1,100 bed Canadian academic tertiary care centre) were searched to identify all patients who underwent PPS FNA from September 1991 to August 2009. The FNA diagnosis was compared to the gold standard of subsequent histopathology or long-term clinical follow-up. Of 36 FNAs, 3 employed image guidance. Eleven (31%) FNAs were nondiagnostic. In the 25 diagnostic FNAs, there was sensitivity 89%, specificity 94%, PPV 89%, NPV 94%, and accuracy 92% for the diagnosis of positive or negative for malignancy. A correct specific diagnosis was made in 9/25 (36%) cases. The nondiagnostic rate was significantly higher (P < 0.025) in FNAs prepared as conventional smears (9/17 = 53%) versus LBC (2/19 = 11%). A specific diagnosis was made significantly more often (P < 0.05) with LBC (8/19 = 43%) versus conventional smear (1/17 = 5.9%). One minor complication from FNA occurred. In conclusion, PPS FNA is safe and accurate for the diagnosis of malignancy. The rate of reporting a specific diagnosis is low. Nondiagnostic FNAs are common. There are more specific diagnoses and fewer nondiagnostic tests with LBC than with conventional smears. Improved specimen quality with LBC is likely a factor.

Surgical treatment of parapharyngeal space tumors: A report of 29 cases

“…FNAC of PSS tumors is performed for lesions of the prestyloid PPS and may allow for the differentiation of salivary gland malignancies. Needle biopsy of the poststyloid PPS carries the risk of vascular complications (22), and its use is also limited in cases of the diagnosis of hemorrhagic specimens in paragangliomas and hypocellular specimens in schwannomas (23,24). A flow chart of the complete preoperative examination process is presented in Fig.…”

Clinical diagnosis and treatment outcomes for parapharyngeal space schwannomas: A single‐institution review of 21 cases

“…Diagnostic performance of ultrasound‐guided FNAC for PPS tumors was shown to be relatively low . Moreover, no studies have shown the usefulness of FNAC in cervical schwannomas, and the accuracy of FNAC has been reported to be 20.0%‐30.3% . FNAC is likely not essential in cases of suspected schwannoma, because cell sampling per se is not only very difficult due to strong intercellular binding but also carries the risk of injury of the involved nerve.…”

A field guide for cancer diagnostics using cell‐free DNA: From principles to practice and clinical applications

“…Reported sensitivities are 64%‐82% in a routine diagnostic setting and even higher in study settings, and detection of allele frequencies as low as 0.1% can be achieved. Here, sampling error may play a role since mutated cfDNA molecules might not be present in each replicate . Therefore, samples should always be analyzed in triplicates if low allele frequencies are expected …”

“…119 The use of locked nucleic acid (LNA) probes further enhances the sensitivity for mutations as the amplification of wild type alleles is suppressed. 120 Physical partitioning of PCR reactions can be achieved by chip-based systems using microwell plates (Quantstudio 3D, Thermo Fischer Scientific) 47,117 or microfluidic systems for parallel PCR reactions (Fluidigm) 121,122 as well as by oil emulsion-based droplet systems, including droplet dPCR (Bio-Rad), 123 picoliter droplet-based dPCR (RainDance), 100 and BEAMing. 124,125 Comparable to qPCR assays, the ability of dPCR as well as ddPCR to perform multiplex analysis is limited.…”

“…Here, sampling error may play a role since mutated cfDNA molecules might not be present in each replicate. 120 Therefore, samples should always be analyzed in triplicates if low allele frequencies are expected. [131][132][133] Although dPCR and ddPCR are cheaper and have lower turnaround times than NGS-based approaches when testing for single mutations only, the main disadvantages are that mutations have to be tested sequentially and that detection of previously unknown mutations is impossible.…”