Role of fine needle aspiration in malignant parotid tumors at a single-center experience: A retrospective cohort study

Abstract

Background

Parotid gland tumors are mostly benign with good prognosis. On the other hand, malignant tumors of the parotid gland often have poor prognosis and metastasize. Mucoepidermoid carcinoma is the most common cancer in the parotid gland accounting for nearly 40–50% of the cases. Therefore, it is important to define the role of fine needle aspiration in differentiating between different types of parotid malignancies.

Method

This is a retrospective chart review study that was done on 49 consecutive patients who underwent parotid surgeries in King Fahad Armed Forces Hospital in Jeddah, Saudi Arabia, between Jan 2003 and Feb 2020. The records of 49 patients were obtained, fine needle aspiration and pathology reports were reviewed to define the role of fine needle aspiration in diagnosing malignant parotid tumors by calculating the sensitivity, specificity, positive predictive value, and negative predictive value.

Results

Retrospective analysis of 39 cases revealed that there was one case which was diagnosed for cancer was missed by fine needle aspiration. Meanwhile, six cases were diagnosed as malignant lesions using both fine needle aspiration and histopathology. Furthermore, 30 cases were determined benign based on fine needle aspiration and histopathology. The sensitivity of fine needle aspiration for detecting malignancy was 85.7%, specificity was 93.8%. positive predictive value of 75% and negative predictive value of 96.7%.

Conclusion

Fine needle aspiration is highly sensitive and specific for parotid tumors. We support the role of pre-operative FNA for all parotid tumors as its accurate in differentiating between benign and malignant lesions.

Highlights

• •40–50% of the cases of parotid gland carcinoma is Mucoepidermoid.
• •It is important to be able to differentiate between types of parotid tumors.
• •FNA accuracy is variable among studies in Saudi Arabia.

1. Introduction

Parotid gland plays a major role in the secretion of saliva as it is the largest salivary gland in the human body. Tumors of salivary glands account for nearly 5% of all head and neck tumors with 75% arising from the parotid glands [1]. Moreover, 80% of parotid gland tumors are considered benign with the most common types being mixed tumors and warthin's tumors [1]. Parotid gland malignancy is considered rare and has a slow-growing rate with a tendency to having an aggressive nature if not detected early [2]. Furthermore, malignant tumors can originate from the parotid gland as primary malignant tumors or metastasize to surrounding structures. Meanwhile, mucoepidermoid carcinoma is the most common cancer in the parotid gland accounting for nearly 40–50% of the cases [2,3].

Parotid tumors has variable prognosis according to the histological type and stage of the malignancy and are treated using a combination of surgical and radiational therapy. However, mortality often occurs due to metastasis spread, especially to the lung, rather than from direct extension. Risk factors that have been associated with decreased survival include male gender, old age, tumor size ≥4 cm, extraparenchymal extension, lymph node involvement or distant metastasis [3]. Therefore, early evaluation and diagnosis improves chance of early proper management.

The initial diagnostic approach is taking a biopsy by Fine Needle Aspiration (FNA) and is considered safe, rapid and cost effective [4,5]. Meanwhile, the gold standard for diagnosing parotid tumors is the histopathology of the resected tumor to differentiate either it is a benign or a malignant form of tumors. However, FNA carries a challenge in diagnosing parotid tumors and the accuracy of the diagnosis is variable as it is operative dependent.

Due to the limitations of the local studies that assess FNA accuracy, we are aiming to evaluate the accuracy of FNA in detecting benign and malignant parotid lesions subtypes in comparison to post-surgical tumor resection histopathology among patients in King Fahd Armed Forces Hospital, Jeddah, Saudi Arabia.

2. Methods

This is a retrospective chart review study which was carried out in King Fahad Armed Forces Hospital, Jeddah, between Jan 2003 and Feb 2020. The study was approved by the institutional board review (IRB) of King Fahad Armed Forces Hospital and registered in research registry with ID: researchregistry6565. All consecutive patients with benign and malignant parotid diseases undergoing superficial or total parotidectomy were included. A total of 49 patients were obtained initially. The patient records were reviewed, and data on age, gender, history of previous surgery, and details of FNA and postoperative pathology reports were recorded on data sheets. Afterwards, 10 patients were excluded due to missing FNA or non-conclusive reports. Only patients who underwent ultrasound guided FNA were included. FNA and final pathology reports were recorded for 39 patients and the role of FNA in diagnosing malignant parotid tumors was assessed by measuring sensitivity, specificity, positive predictive value, and negative predictive value. We used the Statistical Package for the Social Sciences (SPSS) software (version 25; IBM, Armonk, New York) to perform all the statistical analyses. The study has been reported with accordance to the strengthening the reporting of cohort studies in surgery (STROCSS 2019) guidelines [6].

3. Results

In our study, 39 consecutive patients were included with a mean age of 51 ± 14.7 with the youngest included patient aged 23 and oldest of 80 years while the majority of patients were males 22 (56.4%). Regarding FNA diagnosis, there was one case of cancer that was missed by FNA, two cases were misdiagnosed as benign by FNA, six cases were diagnosed as malignant lesions using both FNA and histopathology and 30 cases were determined benign based on FNA and histopathology (Table 1). The accuracy of FNA for detecting malignancy was 85.7% sensitivity, 93.8% specificity, 75% positive predictive value, and 96.7%. negative predictive value (Table 2).

Table 1.

Demographics and lesion characteristics.

Variable	N (%)
Age range (Mean ± SD)	23-80 (51 ± 14.7)
Gender Male Female	22 (56.4%) 17 (43.6%)
Diagnosis based on FNA Benign Malignant	31 (79.5%) 8 (20.5%)
Diagnosis based on final histopathology Benign Malignant	32 (82%) 7 (18%)

Table 2.

Analysis of FNA results in relation to the histological findings (N = 39).

Parameter	Histological results
	Positive	Negative	Total
FNA results	• Positive	6	2	8
	• Negative	1	30	31
	• Total	7	32	39
Sensitivity	Specificity	Positive predictive value	Negative predictive value
85.7%	93.7%	75%	96.7%

4. Discussion

FNA is a consistent investigation technique that offers valuable evidence for the preoperative diagnostic work-up [7]. As the complication rate rationally upsurges with the grade of invasiveness of the surgery, it is vital to be capable to distinguish the tumor preoperatively to properly notify the patient about the type of operation that will be done, the need for lymph node dissection and the chances of nerve sacrifice or injury [8]. Because FNA is a cheap, fast and easy technique for preoperative diagnosis and has a low complication rate and morbidity, it is the initial choice of investigation in parotid tumors [9].

In 2011, Ali et al. studied a total of 114 salivary gland and reported the FNA that were undertaken. From those 114, 75 patients were correctly diagnosed by FNA with neoplasms [10]. Another study reported that (78.4%) of the patients, tumor was reported as benign and in (21.6%) patients FNAB diagnosis was suspicious for malignancy, malignant or non-diagnostic. In final histopathologic diagnosis, 42 of the tumors were benign and 9 were malignant [11].

According to our results, the sensitivity of FNA for detecting malignancy was 85.7% and specificity was 93.8% with positive predictive value of 75% and negative predictive value of 96.7%. In comparison to a study conducted on 114 patients in 2016 at King Abdulaziz University Hospital, Jeddah, KSA, they reported a sensitivity of 50%, specificity of 100%, positive predictive value of 100% and negative predictive value of 91.4% [12]. Furthermore, Altin et al. studied 217 cases of FNA in Brazil found that sensitivity, specificity, positive predictive value and negative predictive value were 76.9%, 95.4%, 75% and 95.9%, respectively [13]. In a review of the literature of the last decade, the sensitivity was reported to range between 60% and 92% and the specificity was reported to range between 87.7% and 100% [14]. Another survey showed sensitivity of 88.9%, specificity of 97.9%, positive predictive value of 93%, and negative predictive value of 96.7% and diagnostic accuracy of 95.8% [15]. Other previous studies reported sensitivity 68.96%, specificity 89.63%, positive predictive value 54.05% and negative predictive value 94.23% [16]. Other studies reported that FNA sensitivity and specificity values can be variable in relation to different populations [17,18] where sensitivity varied between 38% [19] and 97% [16] and specificity varied between 81%13 and 100% [20].Furthermore, Dhanani R et al. conducted fine needle aspiration cytology preoperatively and the results were compared with the final histopathology, which showed a sensitivity of 88.9%, specificity of 97.9%, positive predictive value of 93%, and negative predictive value of 96.7% [15].

However, fine-needle aspiration biopsy may have some disadvantages including bleeding, squamous metaplasia, fibrosis, and necrosis in the final histopathological examination. Nevertheless, it is generally accepted that these complications, if they do exist, do not interfere with the definitive diagnosis [21]. Rarely, complications such as bleeding, facial nerve injury, fibrosis, and tumor erosion have been reported.

5. Conclusion

FNA is highly sensitive and specific for parotid tumors. More support for the role of pre-operative FNA should be established for all parotid tumors as its accuracy in differentiating between benign and malignant lesions can be high.

Funding

None.

Annals of Medicine and Surgery

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Appendix A. Supplementary data

The following is the Supplementary data to this article: