| Abstract|| |
Background: Lateral neck swelling in an adult is a common presentation for primary and secondary malignant lesions. Metastasis from squamous cell carcinoma often leads to various secondary changes in the lymph nodes, which makes their diagnosis on cytology a difficult task. Sometimes, the primary sites remain occult and any false negative cytological diagnosis becomes a misleading factor.
Aim: Our aim was to evaluate the efficacy of fine needle aspiration cytology (FNAC) in diagnosing metastasic squamous cell carcinoma in the head and neck, and to highlight the precautions that can reduce the rate of false negative diagnosis.
Materials and Methods: Two thousand five hundred and twelve patients in an age range of 18 to 80 years and presenting with a solitary lateral swelling of the neck were selected for this study.
Results: Three hundred and seventy positive and 45 suspicious cases of metastatic squamous cell carcinoma were detected by FNAC; there were 15 false negative cases. All of them were associated with cystic change, abscess, or necrosis. The primary sites for carcinoma were the tonsil, tongue, pharynx, and larynx. No primary site could be detected in three cases. Histopathological confirmation was done in all the cases. The specificity and sensitivity of FNAC in the detection of positive cases of metastatic squamous cell carcinoma were 96.05 and 96.5% respectively.
Conclusions: Any lateral neck swelling in adult patients that is associated with cystic change, abscess, or necrosis on FNAC should be carefully searched for malignant cells. Clinical re-evaluation and image guided surgical biopsy should supplement FNAC in suspicious cases. In spite of the possible limitation of a false negative diagnosis, FNAC remains a useful tool in diagnosing metastasis with good certainty.
Keywords: Cytology; metastasis; pitfalls; squamous cell carcinoma.
|How to cite this article:|
Konar K, Ghosh S, Ghosh T, Bhattacharya S, Sanyal S. Pitfalls in the cytodiagnosis of metastatic squamous cell carcinoma in the head and neck: A retrospective study. J Cytol 2008;25:119-22
|How to cite this URL:|
Konar K, Ghosh S, Ghosh T, Bhattacharya S, Sanyal S. Pitfalls in the cytodiagnosis of metastatic squamous cell carcinoma in the head and neck: A retrospective study. J Cytol [serial online] 2008 [cited 2021 Mar 5];25:119-22. Available from: https://www.jcytol.org/text.asp?2008/25/4/119/50795
| Introduction|| |
Any neck mass in an adult that persists longer than a week is pathological unless proven otherwise.  A larger percentage of these masses turn out to be metastatic deposits. The use of fine needle aspiration cytology (FNAC) is an established method for the diagnosis of metastasis in lymph nodes.
The metastasis from squamous cell carcinomas may lead to necrosis, abscess formation, or cystic change, leading to a false negative diagnosis. Moreover, the primary sites sometimes remain occult, contributing to the delay in treatment.
The aim of this study was to analyse the efficacy of FNAC in diagnosing metastatic squamous cell carcinoma of the head and neck and to highlight the precautions that can reduce the rate of false negative diagnosis.
| Materials and Methods|| |
The present study is a retrospective analysis of patients presenting with lateral neck swelling. The inclusion criterion was all patients in the age range of 18 to 80 years with lateral neck swelling. As metastatic squamous cell carcinoma is uncommon in children and adolescents less than 18 years of age, these age groups were not included in the study. Multiple swellings most often represent lesions other than metastatic carcinoma and therefore, patients having more than one swelling were excluded from this study. All the patients were subjected to FNAC using a 22G needle and 20 mL disposable syringe. The smears were divided into two sets: one set was fixed in alcohol and stained with hematoxylin and eosin (H and E) whereas the other set was air dried and stained with May-Grünwald-Giemsa (MGG) stain. A repeat FNAC was done in cases where the yield was inadequate in the first aspiration. FNA smears were examined separately by three different pathologists and the morphology of the cells and their pattern were studied in detail.
The smears were reported as negative, suspicious, or positive for metastatic squamous cell carcinoma. Surgical biopsy and histopathology was done in all cytologically suspected cases of malignancy and in those cytologically benign cases that did not respond to conservative management. Patients whose surgical biopsy reports were not available, were also excluded from the study.
| Results|| |
The total number of cases with lateral neck swelling subjected to FNAC was 2512. Of these 2012 (80.09%) were benign, 495 (19.70%) malignant, and five (0.21%) cases were inconclusive [Table 1]. Among benign lesions, tuberculous lymphadenitis, suppurative lesions, and reactive hyperplasia were common findings, followed by benign cystic lesions, sialadenitis, and salivary adenoma. The malignant lesions consisted of 415 cases of metastatic squamous cell carcinoma, 64 cases of adenocarcinoma, and 16 cases of lymphoproliferative disorder [Table 2]. Out of the 415 cases of metastatic squamous cell carcinoma, 370 cases were positive and 45 cases were suspicious in nature.
The inconclusive cases had inadequate material on FNAC and did not come for follow-up. Among the cytologically diagnosed benign cases, 17 were found to be malignant on subsequent surgical biopsy. Of these, there were 15 cases of metastatic squamous cell carcinoma with secondary changes, one case of metastatic papillary carcinoma from the thyroid, and one with a subcapsular deposit of nasophanyngeal carcinoma [Table 3].
Metastatic deposit from squamous cell carcinoma was found histologically in 430 cases. In 415 cases (96.5%), it was of the solid type, partially or totally involving the lymph node substances and 15 cases had associated secondary changes. Cystic change was detected in seven cases (1.7%), secondary infection and abscess formation in four cases (0.9%), and granulomatous reaction in four cases (0.9%) [Table 4]. The most common primary site for the solid variant of the metastatic deposit was the pharynx accounting for 207 cases (49.8%), followed by 175 cases (42.2%) of the larynx. Metastasis with cystic change was common from the tonsil (three cases) and the tongue (one case). For three such cases, no primary site could be detected. Abscess and granuloma formation was common from squamous cell carcinoma of the tongue [Table 4].
There were 1095 true negative, 15 false negative, and 415 true positive cases of metastatic squamous cell carcinoma detected by FNAC but no false positive case [Table 5]. On the basis of the above observations, the sensitivity of FNAC in detecting metastatic squamous cell carcinoma was 96.5%; the specificity was 100% for the total cytologically diagnosed positive and suspicious cases and 96.05% for only positive cases.
| Discussion|| |
Among the adult patients with isolated palpable lateral neck swelling, approximately 20% were diagnosed as malignancy in the lymph node, mostly metastasis from primary squamous cell carcinoma in the head and neck region [Table 1]. In most cases, they presented as a firm and solid mass in the corresponding chain of the lymph node, the cytological diagnosis of which did not pose any problem.
It has been observed that certain squamous cell carcinoma subsites are more likely to produce metastases that are cystic. These sites predominately include primary tumors of the tonsil tissue from Waldayer's ring.  In our study, out of seven cases with cystic change in the lymph node, three cases had primary squamous cell carcinoma in the tonsil, which was approximately one third of the total number of squamous cell carcinoma found in the tonsil [Table 4]. The histopathology showed liquefaction at the centre of the lymph node, leaving behind a very thin rim of solid area at the periphery. The retrospective corroboration of the cytology smear revealed an occasional, malignant squamous cell [Figure 1]. One case had its primary site in the tongue whereas no primary site could be found for the other three cases [Figure 2]. These cases were kept under close clinical supervision.
Smears with polymorphs and necrosis were diagnosed as abscess and suppurative lymphadenitis [Figure 3]. The histopathology revealed necrotic malignant cells with reactive polymorph infiltration. The primary sites were the tongue (three cases) and the larynx (one case) [Table 4]. Granulomatous lymphadenitis was misdiagnosed from the smears which had necrosis and granuloma formation [Figure 4]. Surgical biopsy showed necrosis of malignant cells and granuloma formation in response to keratinous material. Primary sites were the tongue (two cases), the pharynx (one case), and the larynx (one case) [Table 4].
The aspiration from metastatic nodes with cystic change often becomes hypocellular due to the presence of fluid. Any centrifuged deposit should be very carefully examined for any malignant squamous cells. A repeat aspiration from any palpable mass left after aspiration of fluid may yield cellular material. An image-guided FNAC from the solid area of the swelling can also be helpful.
Smears with large amounts of inflammatory cell infiltration and abscess formation should be carefully searched for malignant squamous cells. The presence of keratinous debris and foreign body giant cell formation indicates the possibility of keratinising squamous cell carcinoma.
A repeat FNAC may be helpful in the smears that are hypocellular, inadequate, or doubtful.
Squamous metaplasia in different benign conditions can mimic well differentiated squamous cell carcinoma on FNAC. As the cells appeared mature in these cases, we gave emphasis to the nuclear features. Malignant features such as hyperchromasia, anisonucleosis, and irregular chromatin clumping are helpful for a confident diagnosis and help in distinguishing metastatic lesions from metaplasia.  Moreover, all the FNAC slides were scrutinised separately by three experienced pathologists in our department.
The 100% specificity of FNAC in our study refers to all the cases originally diagnosed as "positive" and "suspicious" on FNAC. It was 96.05% for only the positive cases and there was no false positive case. This is also consistent with the low rate of false positive cases of metastasis detected by FNAC in previous studies. , Moreover, avoidance of false positive diagnosis is of obvious importance as therapeutic and surgical decisions are often based on cytology reports.
The sensitivity of FNAC was 96.5%. As some of the primary squamous cell carcinomas in head and neck often remain occult,  their first manifestation being lymph node metastasis, any false negative FNAC diagnosis of lymph node metastasis may lead to a delay in the treatment.
Adult patients between 18 to 80 years of age presenting with a lateral cystic neck mass must be presumed to have a cancer until proven otherwise. , The mass should be carefully examined cytologically, keeping the pitfalls in mind. However, as a negative cytodiagnosis can be misleading, clinical revaluation and imageguided surgical biopsy should be advised in suspicious cases to avoid unnecessary delay in the management, affecting the survival of the patient. In spite of the limitations, FNAC remains a useful tool for the diagnosis of metastatic squamous cell carcinoma in the head and neck.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]