|Year : 2019 | Volume
| Issue : 3 | Page : 686-689
Fine needle aspiration cytology of minor salivary gland tumors: A retrospective 5-year study of 42 cases in a tertiary care hospital
Subrata Pal1, Sajeeb Mondal1, Kingshuk Bose2, Rajashree Pradhan1, Arindam Bandyapadhyay3, Debosmita Bhattacharyya4
1 Department of Pathology, College of Medicine and Sagore Dutta Hospital, Kolkata, West Bengal, India
2 Department of Pathology, Bankura Sammilani Medical College, Bankura, West Bengal, India
3 Department of Pediatrics, College of Medicine and Sagore Dutta Hospital, Kolkata, West Bengal, India
4 Department of Pathology, R. G. Kar Medical College and Hospital, Kolkata, West Bengal, India
|Date of Web Publication||29-May-2019|
Dr. Subrata Pal
Kalpataru Apartment, Sahid Colony, BT Road, PS - Khardaha, North 24 Pargana, West Bengal
Source of Support: None, Conflict of Interest: None
Background: Minor salivary gland tumors (MSGTs) are less common than major salivary glands and involve only 15–20% of all salivary gland tumors. Most of the cases originate at intra- and peri-oral region. Minor salivary gland lesion cytology has been studied rarely in India.
Aims: This present study was performed to evaluate the role of fine needle aspiration cytology (FNAC) in diagnosis of MSGTs and to explore the cases of cytohistological discrepancies in the study.
Materials and Methods: This retrospective study was conducted over a 5-year period on 42 cases of MSGTs. In all the cases, cytology was correlated with histology and cytohistological discrepancies were searched. Sensitivity, specificity, and diagnostic efficacy were calculated using histopathology as gold standard.
Results: We diagnosed 27 malignant (64.28%) and 15 benign (35.71%) MSGTs in cytological evaluation. We found two false negative and one false positive case in cytology. Sensitivity, specificity, and diagnostic accuracy of the study were 92.59%, 93.33%, and 92.85%, respectively.
Conclusion: FNAC is a minimally invasive and cost-effective procedure with high accuracy (92.85%) in the assessment of MSGTs and helps in the management of benign and malignant tumors.
Keywords: Cytology, discrepancy, fine needle aspiration cytology, histology, minor salivary gland tumors
|How to cite this article:|
Pal S, Mondal S, Bose K, Pradhan R, Bandyapadhyay A, Bhattacharyya D. Fine needle aspiration cytology of minor salivary gland tumors: A retrospective 5-year study of 42 cases in a tertiary care hospital. J Can Res Ther 2019;15:686-9
|How to cite this URL:|
Pal S, Mondal S, Bose K, Pradhan R, Bandyapadhyay A, Bhattacharyya D. Fine needle aspiration cytology of minor salivary gland tumors: A retrospective 5-year study of 42 cases in a tertiary care hospital. J Can Res Ther [serial online] 2019 [cited 2020 Nov 27];15:686-9. Available from: https://www.cancerjournal.net/text.asp?2019/15/3/686/191055
| > Introduction|| |
Salivary gland tumors constitute 2–6.5% of head and neck tumors. Minor salivary gland tumors (MSGTs) are less common than major salivary gland tumors and account only 15–20% of all salivary gland neoplasms. Most of the MSGTs originate from palate, oral cavity and lips. Fine needle aspiration cytology (FNAC) is a well-established and widely used diagnostic tool for the evaluation of superficially located lesions as well as for swelling of major salivary glands. It is a rapid, inexpensive, minimally invasive diagnostic mean, and also helps to determine the therapeutic protocol. However, diversity of salivary gland lesions, difficulty in aspiration of intra-oral lesions and relatively rarity of the tumors have lead to minimal research work on cytodiagnosis of minor salivary gland lesions at past era. The present study was undertaken to evaluate the type and distribution of MSGTs and role of FNAC in diagnosis of the neoplasms. We wanted to focus the cases of cytohistological discrepancy by correlating with histopathological diagnosis.
| > Materials and Methods|| |
The present study was conducted in our institute from January 1, 2009 to December 31, 2014. Ethical approval was taken from the Institutional Ethical Committee. The study was conducted on 42 patients, who were diagnosed as neoplastic minor salivary gland lesions in cytology (FNAC). Written consents were obtained from all the patients included in the study group. We collected data about history (age, presenting complaints, signs, and symptoms) and detailed clinical examination (bilaterality, lymphadenopathy and signs related to metastasis) in each case. We selectively excluded eight nonneoplastic cases during the data collection. Data were collected retrospectively from records of the department of cytology. FNAC was performed by using 22–23G needle attached with 20 ml syringe. Smears were fixed in 95% ethanol for Papanicolaou staining and air dried for Leishman and Giemsa staining. Cytological diagnoses were done depending on standard cytomorphological criteria. After surgery, all excised specimens were sent to our histopathology laboratory. All biopsy specimens were undergone successive fixation steps in formalin, processing by standard procedures, embedding in paraffin, section cutting, and staining with Hematoxylin and Eosin. Histopathology examination was regarded as final diagnosis. All the cytology slides of all cases were reviewed and correlated with histological diagnosis to find out the possible causes of error in cytology.
| > Results|| |
The present study included 42 cases of MSGTs over a period of 5 years. Sex ratio of male and female was 1.8:1. Patients ranged in age from 11 to 72 years with a median age of 42.33 years. Age distribution of the cases is presented in [Figure 1], showing large number of cases are catering between 31 and 50 years of age (23 cases, 54.76%). Most common site in our study was hard palate (22 cases, 52.38%). Other sites were cheek (eight cases, 19.04%), lower lip (six cases, 14.28%), upper lip (7.14%), floor of mouth (two cases, 4.76%), and tongue (one case, 2.38%) [Table 1]. We have selectively excluded eight nonneoplastic minor salivary gland lesions from our study because we wanted to focus on the neoplastic cases. None of the nonneoplastic lesions was biopsied. We diagnosed 27 malignant cases (64.28%) and 15 benign minor salivary gland neoplasms (35.71%) in our study [Table 2]. Most common malignant tumor in the present study was adenoid cystic carcinoma accounting 18 cases in cytology as well as in histopathology. Other malignant tumors were mucoepidermoid carcinoma (six cases, 14.28%), polymorphous low grade adenocarcinoma (two cases, 4.76%), and adenocarcinoma – not otherwise specified (one case, 2.38%). Most common benign tumor in our study was pleomorphic salivary adenoma (PSA) (13 cases, 30.95%). We found two cases (4.76%) of basal cell adenoma in our series. One of these was cytologically misinterpreted as PSA.
|Figure 1: Bar diagram representing age distribution of cases of minor salivary gland tumors|
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|Table 2: Distribution of the cases according to cytology and histological diagnosis|
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On comparison with cytological diagnoses, we found two false negative cases and one false positive case in our study. Two cases were nondiagnostic even after repeated aspiration due to poor cellularity, which were finally diagnosed as PSA on histopathology. Sensitivity and specificity of cytology in the present study were 92.59% and 93.33%, respectively. Positive predictive value of the present study was 0.96. Diagnostic accuracy of FNAC in diagnosing MSGTs in the present study was 92.85%.
| > Discussion|| |
We have studied 42 cases of MSGTs from intra- and extra-oral region. Most of the previous study exhibited female preponderance with a ratio of 1:1.2 (M: F) to 1:1.9.,, But in the present study, we found an altered sex ratio of 1.8:1 (M: F). Cause of such alteration of sex ratio is unknown. Mean age of malignant minor salivary tumors (47.5 years) is higher than the benign lesions (32.07 years). Similar finding is also experienced by Waldron et al., but not by Moshy et al. and Jansisyanont et al.,, In the present study, we found greater number of malignant salivary gland tumors (27 cases, 64.28%) than the benign (15 cases, 35.72%) neoplasms. In most of the previous studies malignant tumors comprised 63–82% of all MSGTs, consistent with our study.,, Vaidya et al. explained the very high number of malignant cases as a referral bias in their study. Most common site of MSGTs in the present study was hard palate (22 cases, 52.38%), consistent with most of the previous studies.,,, Other sites of involvement were cheek, lower lip, upper lip, floor of mouth, and rarely tongue. Most frequent benign tumor in the present study was PSA accounting 13 cases (30.95%). Incidence of PSA varied from 21.3% to 70% in different series but most of authors reported the incidence below 50% of all minor salivary gland neoplasms., Adenoid cystic carcinoma was most frequent (18 cases, 42.85%) malignancy in our study, whereas mucoepidermoid carcinoma was less common (six cases, 14.28%). Our findings correlate well with other similar studies.,,, Jansisyanont et al. and some other authors found mucoepidermoid carcinoma as the commonest minor salivary gland malignancy in their studies.,,, Buchner et al. suggested the possibility of geographic and ethnic differences in the different incidence of adenoid cystic and mucoepidermoid carcinoma.
Though FNAC is a very common diagnostic tool in head and neck region, till the use of FNAC in intra-oral lesions is limited. As MSGTs are less common and majority of MSGTs occur at intra- or extra-oral locations, cytological approach of diagnosis is uncommon. In the present study, we found two false negative cases and one false positive case during comparison with histopathology. Sensitivity and specificity of the present study were 92.59% and 93.33%, respectively. Similar diagnostic yield was found in a study by Mondal et al. In similar studies, Gupta et al. and Singh et al. found less sensitivity (71.4% and 77.7%, respectively), and higher specificity (97.8% and 100%, respectively)., The difference between sensitivity of the present study and other similar studies is possibly due to selective retrospective inclusion of MSGTs and inclusion of extra-oral MSGTs in the present study. Diagnostic accuracy of the present study (92.85%) corresponds well with other previous authors (Gupta et al. – 87.7%, Singh et al. −100%).,
Regarding cytohistological discrepancies, we found two false negative cases of polymorphous low grade adenocarcinoma which was diagnosed as PSA in cytology [Table 3]. Both the cases were palatal lesions and cytology revealed highly cellular smears having clusters of round to oval neoplastic cells with fibromyxoid stroma. The tumor cells had moderate to scanty cytoplasm with round to oval nuclei, minimal pleomorphism, and inconspicuous nucleoli [Figure 2]a and [Figure 2]b. Similar errors have been experienced by Sing et al. and Sahai et al., We have missed the palisading of tumor cells around the myxoid stroma which is useful for the diagnosis of polymorphous low grade adenocarcinoma as mentioned by Watanabe et al.
|Figure 2: (a) Photomicrograph of cytology of polymorphous low grade adenocarcinoma misinterpreted as pleomorphic salivary adenoma (Leishman and Giemsa stain, High power 40× view). (b) Photomicrograph of histology of polymorphous low grade adenocarcinoma (corresponding of Figure 2a) (H and E, low power 10× view)|
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Another case of cytohistological discrepancy was a 44 years male with a swelling at floor of mouth. Cytology of the lesion revealed clusters of oval neoplastic cells with squamous metaplasia with some ciliated glandular cells in a blood mixed background. The smears were cytologically diagnosed as mucoepidermoid carcinoma [Figure 3]a. On histopathology, it was diagnosed as PSA with extensive squamous metaplasia [Figure 3]b. Neoplastic cells with squamous metaplasia, some ciliated glandular cells in a blood mixed background and paucity of chondromyxoid stroma leaded to such misdiagnosis. Similar error has been documented previously in case of multicystic PSA, where cytology lacks chondromyxoid stroma and exhibit extensive squamous metaplasia.,, Multiple sampling from different areas and help of immunocytochemistry can avoid such fallacy. Another case of basal cell adenoma of floor of the mouth was cytologically interpreted as PSA. Cytology of the case revealed highly cellular smears comprised benign epithelial cells in cohesive clusters along with dense stromal matrix [Figure 4]. The cells exhibited scanty cytoplasm, round to oval small nuclei with inconspicuous nucleoli. Basal cell adenoma is frequently misinterpreted as PSA on cytology smears, experienced by many previous authors. We failed to distinguish the scanty eosinophilic stroma from typical fibrillar chondro-myxoid stroma of pleomorphic adenoma. Typical sharp demarcation of epithelial stromal interface and peripheral palisading of cells were not clearly visualized, which has mislead our interpretation.
|Figure 3: (a) Photomicrograph of cytology of metaplastic squamous cells in the case of pleomorphic salivary adenoma with extensive squamous metaplasia (L and G stain, high power 40× view). (b) Photomicrograph of histology of pleomorphic salivary adenoma with extensive squamous metaplasia (respective of Figure 3a) (H and E, low power 10× view)|
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|Figure 4: (a) Photomicrograph of cytology of basal cell adenoma misinterpreted as pleomorphic adenoma (L and G, high power 40× view). (b) Photomicrograph of histology of corresponding case of basal cell adenoma [Figure 4a] (H and E, low power 10× view)|
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| > Conclusion|| |
MSGTs are less common and rarely approached with FNAC for preoperative cytological diagnosis. But FNAC has excellent sensitivity, specificity, and diagnostic efficacy in diagnosis of these lesions. We hope our study will encourage further the clinician and pathologist for preoperative cytoevaluation of MSGTs, which can help in management of the cases.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3]