Fine Needle Aspiration Cytology of Lymph Nodes in Metastatic Cancer and Lymphoma: Our Single-institution Experience

Abstract

Background:

Lymphadenopathy is a common finding in clinical practice. The cause of enlarged nodes on clinical examination alone is challenging and there may be multiple reasons for this enlargement. It may become enlarged due to stimulation by infectious agents or the involvement of metastasis or malignant diseases, such as lymphoma.

Objective:

The aim of the study was to investigate the diagnostic role of fine needle aspiration cytology of lymph nodes in metastatic cancer and lymphoma.

Methods:

A total of 48 FNAC lymph nodes suspicious for malignancy were sampled with follow-up biopsy in Clinical Center of University of Sarajevo from 2017 to 2023. Lymph nodes were aspirated using 20-22 G needle with minimally 2 passes, spread on slides, air-dried, stained with May-Grünwald-Giemsa or Papanikolaou and residual material sent for cytoblock.

Results:

Out of 48 cytological samples, 30 (62.5%) revealed metastatic epithelial cells and 12 (25%) lymphoproliferative neoplasm. Three samples were suspected for malignancies, one sample was unrepresentative, one inconclusive and one falsely negative. Histopathological confirmation had 35 patients, while others were confirmed based on clinical presentation and radiological techniques. Compared to histopathological diagnosis, cytology had a sensitivity of 89.47%, specificity of 93.33%, positive predictive value (PPV) 95.04% and negative predictive values (NPV) 86.13% for epithelial metastatic cancer. The overall diagnostic test accuracy was 91.06%. For lymphoproliferative neoplasms cytology in comparison to histopathology had sensitivity 85.71%, specificity 91.18%, PPV 76.4% and NPV 95.04%. The overall diagnostic test accuracy was 89.81%. In both ways cytology is showing significant possibility to be used as a primary tool in detecting cancers.

Conclusion:

FNAC is a fast, reliable, and efficient method for diagnosing malignant lymphadenopathy. The cytological diagnosis can sometimes be accepted as the definitive diagnosis without further correlation with histopathology, especially in advanced malignancies and known primary malignancies.

1. BACKGROUND

Fine needle aspiration cytology (FNAC) stands as a widely utilized initial diagnostic and management tool for patients presenting with lymphadenopathy, owing to its esteemed advantages of minimal invasiveness and wide diagnostic capabilities (1). Lymphadenopathy is a common finding in clinical practice. The cause of enlarged nodes on clinical examination alone is challenging and there may be multiple reasons for this enlargement (2). It may become enlarged due to stimulation by infectious agents or the involvement of metastasis or malignant diseases, such as lymphoma.

Tissue biopsy is the most reliable diagnostic method for finding the cause of enlarged lymph nodes, but it is invasive and costly, which also limits its use. The limitations of tissue biopsy have led to the use of FNAC. Fine needle aspiration cytology of lymph nodes has advantages and become an integral part in the initial diagnosis and management of patients with lymphadenopathy due to the early availability of results, simplicity, and minimal trauma with fewer complications (3, 4). Recent studies have shown that FNAC has a high accuracy in the diagnosis of reactive lymphoid hyperplasia, infection, lymphadenitis and metastatic malignancy (5).

The diagnosis of metastatic tumors within lymph nodes through cytological smear analysis is of paramount importance and holds a notably high level of reliability. This diagnostic approach serves as the primary indication for initiating a search for the primary tumor, particularly in instances of occult carcinoma (6). Most metastatic cancers can be identified by their cytomorphological features alone. Nevertheless, there exist certain situations where the distinguishing features of different tumors overlap, rendering the precise identification of the primary tumor uncertain (7). In the literature, some studies have shown that FNAC is highly reliable in diagnosing lymph node changes, but there are also some studies to the contrary.

This study sought to examine the diagnostic accuracy of FNAC findings in lymph nodes that displayed clinical and radiological indications of malignancy, in comparison to the results obtained through histopathological examination.

2. OBJECTIVE

Objective of this study was to investigate the diagnostic role of fine needle aspiration cytology of lymph nodes in metastatic cancer and lymphoma.

3. MATERIAL AND METHODS

A total of 48 FNAC lymph node suspicious for malignancy were sampled and collected in Clinical Center of University of Sarajevo and Faculty of Medicine of University of Sarajevo. The ethics committee of the Faculty of Medicine of University of Sarajevo have approved this study. Signed informed consent was obtained from all participants before the procedure. The samples were taken between 2017 and 2023 year. Samples were obtained by two experienced interventional radiologists. Lymph nodes were sampled under ultra-sonography (US) or computerized tomography (CT) guidance. Lymph nodes were aspirated with 20 ml syringe using 20-22 G needle with at least 2 passes. Aspirated materials were spread directly on slides, air-dried, and stained with May-Grünwald-Giemsa stain or Papanikolaou.

Some of them were additionally analyzed on cell blocks (CB). For preparing CB the rest of material collected from needle hub immediately fixed in formalin then centrifuged at 3000 rpm for 10 minutes using Clark fixative (87.5 ml 100% ethanol and 12.5 ml acetic acid) and finally prepare paraffin embedded block. Cell blocks were cut into 4-μm sections and stained with Hematoxylin and Eosin (HE). Slides and CB were interpreted by cytologist or pathologist. Immunohistochemistry was applied on CB or smears when diagnosis based on morphology alone was not able to establish. In the case of suspected lymphoma, if there was adequate amount of aspirate, sample was sent in the transport media for flow cytometry analyses.

The statistical analyses were conducted using R-Studio build 353. Sensitivity, denoting the probability of a positive test result when the disease is present, was assessed. Specificity, indicating the probability of a negative test result when the disease is absent, was also examined. Furthermore, the study explored the positive predictive value, signifying the probability of the disease being present when the test yields a positive result. Additionally, the negative predictive value, representing the probability of the disease’s absence when the test result is negative, was analyzed. The study also considered accuracy, which reflects the overall probability of correctly classifying a patient. The values for sensitivity, specificity, disease prevalence, positive and negative predictive values, and accuracy were reported as percentages. For sensitivity, specificity, and accuracy, confidence intervals were calculated using the “exact” Clopper-Pearson method.

4. RESULTS

The basic clinical data of the patients are presented in Table 1. From that number, 16 (33.3%) were taken from male patients, and 32 (66.7%) from female patients. Average age was 61.75±14.85 years, with no significant differences based on gender (t=0.573, p=0.569) (Table 1).

Table 1. Clinical characteristics of patients with lymphadenopathy.

		Count	% total patient sumber
Sex	Male	16	33.3%
	Female	32	66.7%
Age	do 55 years	13	27.1%
	56-72 years	23	47.9%
	73+ years	12	25.0%
Symptoms	No	29	60.4%
	Yes	19	39.6%
Symptoms	Nausea	1/19 (5,3%)	2.1%
	Weight loss	4/19 (21.1%)	8.3%
	Frequent Difficulty Urinating	2/19 (10.6%)	4.2%
	Pain	7/19 (36.8%)	14.6%
	Icterus	1/19 (5.3%)	2.1%
	Fatigue	3/19 (15.8%)	6.3%
	Vomiting	1/19 (5.3%)	2.1%
	Non-specific symptomatology (fever, diarrhea)	7/19 (36.8%)	14.6%
	Cough	4/19 (21.1%)	8.3%
	Difficulty breathing	2/19 (10.6%)	4.2%

Some type of symptom was present in 19 (39,6%) patients. Most common symptoms were pain and some non-specific symptomatology, occurring in 14.6% of patients, or 36.84% patients that had symptoms. Lymph nodes in the neck were the most common site for FNAC, with 19 (39.6%) of patients having samples taken from there. There were 10 (20.8%) samples taken from the abdomen, 6 (12.5%) from the axilla, 6 (12.5%) from supraclavicular nodes, 4 (8.3%) from the groin, 2 (4.2%) from the submandibular area and one (2.1%) from the infraclavicular node.

The results of the cytological analysis are shown in Figure 1. Cytological analyses found that 30 (62.5%) had metastatic epithelial cells, 12 (25%) had cells consistent with a lymphoproliferative neoplasm. Three samples were reported cytologically as suspected malignancies without ability to differentiate type of tumor. In these three cases histopathological examination revealed that one of them was metastatic neuroendocrine carcinoma and two were Non-Hodgkin lymphomas (NHL).

Figure 1. Cytology findings.

One sample was unrepresentative due to lack of tissue, while after needle biopsy NHL was confirmed. One sample on cytology was inconclusive, and it was later proven to be metastatic breast cancer. One sample with a false-negative cytology result was found to be Hodgkin’s lymphoma (HL) on histopathological analysis (Table 4). Histopathological confirmation was present in 18 (60%) cancers of epithelial cell type (Table 2). Of 12 lymphoproliferative cancers, 11 (91.7%) had histopathological confirmation (Table 3). A total of 13 patients had no histopathological confirmation, but the cytological finding was consistent with a known primary tumour in 6 patients. Samples from 5 patients had an unquestionably cytological finding and histopathological confirmation was not requested. Samples from 2 patients underwent additional immunohistochemistry on cytoblocks. Of these, one patient had proven metastatic breast cancer and the other had lung cancer. In 18 metastatic cancers of epithelial cells, cytological smears showed weak cellularity in one sample (5.56%), satisfactory cellularity in 14 (77.78%), hypercellularity in 2 (11.12%) and unsatisfactory cellularity in one (5.56%). On the cytological block, 9 (50%) samples had unsatisfactory cellularity, 3 (16.67%) had weak cellularity, and 6 (33.33%) had satisfactory cellularity. Of 11 primary lymphoproliferative neoplasms on cytological smear, 9 (81.81%) had satisfactory cellularity and 2 (18.19%) had weak cellularity. On cytological block 6 (54.54%) had unsatisfactory cellularity, 4 (36.36%) had satisfactory cellularity and one (9.1%) sample had weak cellularity (Table 2).

Table 4. Histopathology of cytology suspicious malignant and non-diagnostic lesions. HL – Hodgkin’s lymphoma, NHL–Non Hodgkin’s lymphoma, DLBCL–Diffuse Large B-Cell Lymphoma.

Cytology diagnosis	Histopathology diagnosis	Histopathology vs. Cytology matching
Suspected malignant lesion	Metastatic neuroendocrine carcinoma	-
Suspected malignant lesion	NHL marginal zone	-
Suspected malignant lesion	NHL - DLBCL (ABC subtype)	-
Inconclusive finding	Metastatic breast cancer	-
Unrepresentative sample	B cell lymphoma	-
False negative	HL	-

Table 2. Metastatic epithelial cancers: cytology vs. histopathology. *Cytology detected carcinoma (unknown origin), with matching of carcinoma determined by histopathology.

Cell type	Cytology diagnosis	Origin	Cytology smear cellularity	Cytology block cellularity	Histopathology done	Histopathology vs. Cytology matching
Epithelial	Metastatic carcinoma of transitional epithelium	Urinary bladder	Hypercellular	Satisfying	Yes	+
	Metastatic breast cancer	Breast	Hypercellular	Weak	Yes	+
	Metastatic adenocarcinoma	Unknown	Satisfying	Satisfying	Yes	+
	Metastatic adenocarcinoma	Ovaries	Satisfying	Unrepresentative	Yes	+
	Metastatic lung adenocarcinoma	Lungs	Satisfying	Weak	Yes	+
	Metastatic breast adenocarcinoma	Breast	Satisfying	Unrepresentative	Yes	+
	Metastatic renal cell carcinoma (RCC)	Kidney	Satisfying	Weak	Yes	+
	Metastatic breast cancer	Breast	Satisfying	Unrepresentative	Yes	+
	Metastatic ductal carcinoma of the breast	Breast	Satisfying	Unrepresentative	Yes	+
	Metastatic breast adenocarcinoma	Lungs	Satisfying	Unrepresentative	Yes	+
	Metastatic microcell lung cancer	Lungs	Satisfying	Satisfying	Yes	+
	Metastatic cancer of unknown origin	Unknown	Satisfying	Unrepresentative	Yes	+
	Metastatic breast cancer	Breast	Satisfying	Unrepresentative	Yes	+
	Metastatic cancer of unknown origin	Unknown	Satisfying	Unrepresentative	Yes	+/-*
	Metastatic thyroid cancer	Thyroid gland	Satisfying	Unrepresentative	Yes	+
	Metastatic lung cancer (NSCLC)	Lungs	Satisfying	Satisfying	Yes	+
	Metastatic papillary carcinoma of the thyroid gland	Thyroid gland	Weak	Satisfying	Yes	+
	Metastatic squamous cell nasopharyngeal carcinoma	Nasopharynx	Unrepresentative	Satisfying	Yes	+

Table 3. Primary lymphoproliferative cancers: cytology vs. histopathology. *Cytology detected lymphoma and histopathology revealed subtype of lymphoma, HL – Hodgkin’s lymphoma, NHL – Non Hodgkin’s lymphoma, DLBCL – Diffuse Large B-Cell Lymphoma, SLL/CLL - Small lymphocytic lymphoma/Chronic lymphocytic leukemia.

Cytology diagnosis	Histopathology diagnosis	Cytology smear cellularity	Cytology block cellularity	Histopathology vs. Cytology matching
Lymphoproliferative neoplasm	NHL	Weak	Satisfying	+
B cell lymphoma	NHL-DLBCL	Satisfying	Unrepresentative	+
B cell lymphoma,	NHL-DLBCL	Satisfying	Weak	+
Lymphoma of germinal center origin	NHL-DLBCL	Satisfying	Satisfying	+/-*
Lymphoproliferative neoplasm	HL	Satisfying	Unrepresentative	+
Lymphoproliferative neoplasm of germinal center cell origin	NHL-DLBCL	Satisfying	Unrepresentative	+/-*
B cell lymphoma	NHL-DLBCL	Satisfying	Unrepresentative	+
Mantle cell lymphoma	Mantle cell lymphoma	Satisfying	Satisfying	+
B cell lymphoma	SLL/CLL	Satisfying	Satisfying	+
B cell lymphoma	NHL-DLBCL	Satisfying	Unrepresentative	+/-*
Lymphoproliferative neoplasm, susp HL	HL	Weak	Unrepresentative	+

Of the total number of samples, 35 had histopathological confirmation and others were confirmed based on clinical presentation and radiological techniques. Only samples with histopathological diagnosis were included in the analyses of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and overall test accuracy. For epithelial metastatic cancers and primary lymphoproliferative neoplasms, sensitivity, specificity, positive predictive value, negative predictive value and accuracy were calculated based on these findings (Table 5).

Table 5. Cytology sensitivity, specificity, PPV and NPV compared to histopathology. PPV – Positive Predictive Value, NPV – Negative Predictive Value.

	Epithelial metastatic cancers	Lymphoproliferative neoplasms
Sensitivity (95% CI)	89.47% (66.86% to 98.70%)	85.71% (57.19% to 98.22%)
Specificity (95% CI)	93.33% (68.05% to 99.83%)	91.18% (76.32% to 98.14%)
PPV (95% CI)	95.04% (74.15% to 99.23%)	76.40% (51.84% to 90.69%)
NPV (95% CI)	86.13% (62.43% to 95.87%)	95.04% (84.09% to 98.58%)
Accuracy (95% CI)	91.06% (76.17% to 98.09%)	89.81% (77.63% to 96.66%)

In our study, compared to histopathology, cytology had a sensitivity of 89.47%, specificity of 93.33%, PPV of 95.04% and NPV of 86.13% for epithelial metastatic cancer. The overall diagnostic test accuracy was 91.06%. For lymphoproliferative neoplasms cytology in comparison to histopathology had sensitivity of 85.71%, specificity of 91.18%, PPV of 76.4% and NPV of 95.04%. The overall diagnostic test accuracy was 89.81%. In both ways cytology is showing significant possibility to be used as a primary tool in detecting cancers.

5. DISCUSSION

Several studies have investigated the same objective. Supported by clinical and radiological evidence, FNAC serves as a diagnostic approach capable of averting unnecessary surgical procedures and distinguishing between benign and malignant lesions with a notably high degree of accuracy. The South Jordan study evaluated FNAC in the diagnosis of lymph nodes by correlating with histopathological diagnosis. The comprehensive diagnostic assessment demonstrated robust results, with sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy achieving percentages of 95.4%, 94.1%, 95.4%, 94.1%, and 94.9%, respectively (8). A group of authors investigated the efficacy of FNAC in thyroid and non-salivary head and neck masses. The sensitivity, specificity, PPV, NPV and accuracy were 92%, 100%, 100%, 83% and 94%, respectively, based on the FNAC results of 19 lymph nodes. These findings were similar to the rates found in the present study (9). In the paper by Hwa Jeong Ha et al, FNAC was found to have a sensitivity of 97.8%, specificity of 97.5%, PPV of 98.7% and NPV of 97.7% compared to histopathological analysis. The overall accuracy was 97.7% (10). For metastatic carcinoma, our results were in good agreement with the cytological diagnosis rate in the literature for metastatic carcinoma in lymph nodes, which was 90 to 100% (11, 12). The diagnostic accuracy of our lymphoproliferative cases was 89.81%. This was higher than Landgren’s study which found an accuracy of 73.8% [13]. Our results are consistent with those of Keith et al. (3), Al-Mulhim et al. (7) and Al-Alwan et al. (14), who reported diagnostic accuracy of 82%, 86% and 88.5% for non-Hodgkin lymphoma cases, respectively. Yu et al. conducted a comprehensive review encompassing 31 studies published in both Chinese and English. They utilized random-effects models to aggregate data on sensitivity andspecificity. FNAC for lymph node metastasis had a sensitivity of 63% (95%CI 61%-65%); specificity of 99% (95% CI, 98%-99%); diagnostic value of 76.73 (95% CI, 51.98-113.28) (15). In the Indian study from Odisha, 1129 samples were examined by FNAC compared to histopathological diagnosis. Of these, 399 were used to examine the cytology-histopathology correlation. The diagnostic accuracy of FNAC was determined to be 93.98%, with sensitivity at 93.88%, specificity at 94.64%, a positive predictive value of 99.8%, and a negative predictive value of 71.62% (16). All these results are in favor of our study results. In total 13 cases in our study were diagnosed based on cytology, radiological techniques and known history of primary tumor. This suggests that in some cases FNAC alone may be sufficient, especially when the primary tumor is known. If histopathological analyses were done to these patients, test accuracy would probably improve. Cytological block is complementary to cytological smears and may contribute to better results of cytological findings. Limitation of this study is small number of samples particularly in the group of lymphoproliferative disease and lack of material for cytoblock investigation.

6. CONCLUSION

This study showed that FNAC in our institution had an overall diagnostic accuracy of over 91.06% for metastatic cancer and 89.81% for lymphoma. FNAC of lymph nodes can be used as an early method of diagnosis and management of patients with lymphadenopathy due to its simplicity, low complication rate, reduced trauma and early availability of results. Our study suggests that cytological diagnosis can be accepted as definitive diagnosis without further histopathology confirmation in patients with comorbidities, who are not candidate for more aggressive interventions, patients with known primary tumor or advanced stage metastatic cancer or lymphoma with clinical and imaging data support. Additionally, material collected with FNAC can be used for cell block and immunohistochemistry analysis establishing definitive diagnosis like classic histopathology.

Ethics approval:

The ethics committee of the Faculty of Medicine of University of Sarajevo have approved this study. Signed informed consent was obtained from all participants before the procedure.

Availability of data and materials:

All data are stored in the database of first author Sanela Vesnic, and at the Department of radiology at the Clinical Center of University of Sarajevo. Data without patients ID can be obtained, but only after approval from the Clinical Center of University of Sarajevo.

Authors’ contributions:

SV: Resources, Formal analysis, Sample collection, Writing, AJ: Statistical analysis, writing-original draft, Visualization; VS: Methodology, Conceptualization, MD: Sample collection and analysis, Writing, review and editing, investigation. Authors are confirming that the manuscript has been read and approved by all the authors. Final proofreading was made by the first author.

Conflicts of interest:

None.

Financial support and sponsorship:

None.