Role of Fine Needle Aspiration Cytology in the Diagnosis of Parotid Gland Tumors: Analysis of 193 Cases

Original Research Role of Fine Needle Aspiration Cytology in the Diagnosis of Parotid Gland Tumors: Analysis of 193 Cases Rahim Dhanani1  http://orcid.org/0000-0002-5519-862X Haissan Iftikhar1  http://orcid.org/0000-0003-3266-4015 Muhammad Sohail Awan1  http://orcid.org/0000-0001-8323-7350 Nida Zahid1  http://orcid.org/0000-0001-8812-9463 Sehrish Nizar Ali Momin2  http://orcid.org/0000-0002-3322-7450 1Department of Otolaryngology/Head and Neck Surgery at the University Hospital, Aga Khan University Hospital, Karachi, Pakistan 2Section of Post Graduate Medical Education, Aga Khan University Hospital, Karachi, Pakistan Abstract Introduction Parotid gland tumors include a wide variety of inflammatory and neoplastic diseases. The majority of these tumors are benign (80%), which usually require superficial parotidectomy, while the incidence of malignant tumors is lower (20%), requiring more radical surgery with or without neck dissection. The diagnosis cannot be established on the basis of clinical history and simple physical examination and requires complementary diagnostic methods. Fine needle aspiration cytology (FNAC) guided by ultrasound is a widely used diagnostic tool to evaluate parotid swellings. Objective To determine the sensitivity, specificity, positive and negative predictive values and diagnostic accuracy of FNAC in the diagnosis of parotid gland tumors. Methods A retrospective chart review of 193 patients who underwent preoperative FNAC and parotidectomy at the Aga Khan University Hospital, Karachi, Pakistan, from the period of January 2000 to December 2015 was performed. Results Out of 193 patients undergoing parotidectomy, 110 (57%) were males and 83 (43%) were females, the mean age being 48.21 and 43.76 years old, respectively. The mean duration of the symptoms was 41.33 months, and the most common symptom was preauricular swelling present in all patients, followed by pain, which was present in 29 patients (15%) and facial nerve weakness in 6 patients (3.1%). Fine needle aspiration cytology was performed preoperatively and the results were compared with the final histopathology, which showed sensitivity of 88.9%, specificity of 97.9%, positive predictive value of 93%, negative predictive value of 96.7% and diagnostic accuracy of 95.8%. Conclusion Our results suggest that FNAC is relatively an accurate method for preoperative diagnosis of parotid swelling and can prove to be a valuable tool for preoperative counseling of the nature of the disease and prognosis. Keywords: parotid tumor; fine needle aspiration; cytology; parotidectomy; diagnostic accuracy Introduction Salivary gland tumors are a rare entity and account for between ∼ 3 and 10% of head and neck tumors and up to 0.6% of all tumors of the human body.1 2 A total of 80% of the salivary gland tumors involve the parotid gland, and 80% of these tumors are benign.3 The World Health Organization (WHO) has classified parotid tumors as epithelial and nonepithelial tumors. Although this classification is complex, it has been widely accepted across the world because of its advantages regarding the prognostic and therapeutic aspects as, biologically, each tumor behaves differently from another.4 The diagnosis of salivary gland tumors is becoming increasingly difficult due to the presence of a large histological variety of benign and malignant tumors and to the lack of specific tumor markers. However, on the other hand, these tumors are easily accessible and are very good targets for fine needle aspiration.4 Fine needle aspiration cytology (FNAC) is a simple and useful diagnostic modality in the preoperative assessment of parotid swellings. The history of FNAC goes back to the 1920s at the time of World War I, when it came into use simultaneously in United States and Europe.5 6 It is a cytological diagnostic method that is based on the morphology of a cell or group of cells and microparticles of a tissue that are acquired using a needle. Traditional open biopsy of parotid tumors is no longer used due to high chances of tumor spillage and injury to the facial nerve.7 In comparison to this, FNAC is an easily done procedure with minimum risks of complications and no risk of implantation of tumor cells.4 8 Authors have claimed FNAC to be an accurate, cost-effective and safe procedure.9 10 However, some of the authors were of an opinion that it has little influence on the clinical management.11 It helps to differentiate between inflammatory conditions, which may not require surgery, and neoplastic, benign and malignant, which allows to plan properly before any treatment.10 Also, if the pathology is known preoperatively, counselling of the patient and the planning of the surgery becomes much easier.5 The effectiveness of FNAC of parotid tumors is controversial due to the distinct morphology of the parotid gland. Lower ranges of sensitivity and negative predictive value (NPV) can be related to the difficulty in diagnosis of low grade carcinomas, mostly because of complex cell morphology.10 12 13 However, the use of ultrasound (US) increases the accuracy by helping to avoid necrotic and cystic areas and enables to target areas of higher yield.14 In the present study, we describe our experience on the usefulness and accuracy of FNAC in the diagnosis of parotid gland tumors. Objective The objective of the present study was to determine the sensitivity, specificity, positive and negative predictive values and diagnostic accuracy of FNAC in the diagnosis of parotid gland tumors. Methodology After receiving exemption from the ethical review committee, a cross-sectional study was conducted at a private tertiary care center of Karachi, Pakistan. The medical records of patients who underwent parotidectomy from the period of January 2000 to December 2015 were reviewed. A total of 290 parotidectomies with or without neck dissections were performed over the period of 15 years. Of these, 193 patients were included in the present study, in which preoperative FNAC was performed exclusively at our center. The rest of the patients with missing records, previous history of treatment of parotid tumors and preoperative FNAC not performed at our center were excluded from the present study. In all of the patients, FNAC was performed as a part of the preoperative assessment at our center. It was performed at our pathology department using standard technique. A 22 gauge needle attached to a 10 ml syringe by a free hand technique was used. At least two passes were made in each case to obtain adequate biological material for cytological interpretation. The aspirated material was spread on between 2 and 4 slides and fixed immediately. The slides were stained with the Papanicolaou and occasionally with the May-Grunwald Giemsa methods. Keeping the final histopathology as a gold standard, we classified o (...truncated)