The utility of Fine Needle Aspiration Cytology in the Diagnosis of Lymphadenopathy

Introduction: The causes of lymphadenopathy may be varied ranging from reactive to neoplastic. Fine Needle Aspiration Cytology(FNAC) is a simple and inexpensive diagnostic tool to sample cells from superficial and accessible sites. Aims: This study was undertaken to assess the utility of FNAC in evaluating lymphadenopathy and to study the cytomorphological spectrum of lymph node lesions in our region. Settings and Design: A cross-sectional study of two years duration, on patients with lymphadenopathy who came to the Pathology Department for FNAC. Methods and materials: Cytology findings of Lymph node lesions were classified into four categories and were compared with histopathology diagnosis as the gold standard. Statistical Analysis: Data was tabulated according to various parameters. Sensitivity, Specificity, PPV, NPV, and Diagnostic accuracy for detecting malignancy were calculated. Results: The age range of patients included in the present study ranged from 9 to – 78 years. The mean age is 48.92 years and the median is 52 years. The cytological diagnosis was classified as reactive in 20 cases (32.7%), inflammatory in 16 cases (26.2%), lymphoma in 3 cases (4.9%), and 22 cases (36.1%) were metastasis from other sites. Following histopathology, the cases were diagnosed to be 19 reactive lymphadenopathies, 14 inflammatory lesions, 5 lymphomas, and 23 metastasis. The most common site of lymphadenopathy was the cervical region. Conclusions: FNAC has high sensitivity and specificity in differentiating benign lesions from malignant ones. The age, clinical findings, and supporting investigations should be taken into account while diagnosing a lesion as benign or malignant.


Introduction
Lymph nodes are secondary lymphoid organs, inconspicuously distributed throughout the body.
Lymphadenopathy is a common complaint in children and adults alike, encountered often in routine medical practice. As an antigen, whether infectious or neoplastic in origin, picked up by Antigen Presenting Cells from different sites ultimately reach the draining nodes, the causes of lymphadenopathy vary as much as the sites. Excision biopsy, although more reliable for a final diagnosis, is associated with unavoidable expenses due to hospitalization and preparation for a surgical procedure and the ensuing complications [2].
This study was undertaken to assess the utility of FNAC in evaluating lymphadenopathy and the cytomorphological spectrum of lymph node lesions in our region.

Results
Among the 61 cases included in the present study, 29 were males and 32 were females, with a male:

Discussion
Lymphadenopathy is a clinical finding seen in patients of varying age groups. It may be associated with underlying conditions ranging from inflammatory to neoplastic.    Squamous cell carcinoma shows the cervical group of lymph nodes as the most frequent site of metastasis, similar to the results in a study on malignant lesions in lymph nodes [13]. The diagnostic challenges in squamous cell carcinoma occur due to large areas of necrosis and cystic change, inflammatory reactions, and abscess formation [14].
One case of submandibular lymphadenopathy diagnosed on cytology as Squamous cell carcinoma based on cytomorphological features, on excision turned out to be a case of odontogenic carcinoma. (Figure 6a and 6b) Clear cell odontogenic carcinoma is an aggressive tumor with reported cervical lymph node metastasis. Ameloblastomatous pattern of clear cell odontogenic carcinoma shows cells with squamous differentiation, which was noted in the cytology of this case [15]. Metastasis from adenocarcinoma was noted more in supraclavicular lymph nodes. The acinar and papillary pattern of arrangement pointed to the diagnosis in most of the cases (Figure 7), as in the study on metastatic lymph nodes by Ghartimagar et al. Adenocarcinoma appeared to be the most common malignancy in this study, unlike the present study in which squamous cell carcinoma preceded adenocarcinoma in frequency [16]. Two cases of metastatic Malignant Melanoma were included in the present study of which one was reported as mere metastasis from spindle cell neoplasm as pigmented cells were not found on cytology. The other case showed cells with cytoplasmic melanin (Figure 8) and the diagnosis was made easily, and subsequently, a previous history of melanoma was elicited.

Fig-8: Pigmented cells of metastatic melanoma (Pap, 40X).
The characteristic cytology of malignant melanoma includes high cells yield with varying cell morphology, dissociated pattern, anisokaryosis with macronuclei. Cytoplasmic melanin pigment is a clinching feature but may not be always evident.
Misdiagnosis can be avoided by eliciting an appropriate clinical history [17].
Other cases of metastasis included poorly differentiated carcinoma metastasizing to cervical and supraclavicular lymph nodes and Mucoepidermoid carcinoma to a submandibular node. The site of metastasis of these neoplasms correlates well with those in similar studies [7,13].
The sensitivity and specificity of FNAC in diagnosing malignancy correlates well with these parameters in similar studies. (Table 3) [18,19,20]. Diagnostic accuracy stays within the range proposed by Wilkinson et al. in a study of lymph node malignancies [13]. Positive predictive value is similar to and negative predictive value higher in our as compared to similar studies, as no falsepositive case is reported in the present study [18].

Conclusion
FNAC is an ideal tool for the diagnosis of malignant lesions in lymph nodes and helps in avoiding excision biopsy. FNAC has high sensitivity and specificity in differentiating benign lesions from malignant ones. The present study showed inflammatory lesions as the major cause of lymphadenopathy in younger age groups and metastatic malignancies as the major cause in the elderly. Low-grade lymphomas were mistaken for non-neoplastic conditions in cases with no clinical suspicion of malignancy. The age, clinical findings, and supporting investigations should be taken into account while diagnosing a lesion as benign or malignant.
What does the study add to existing knowledge FNAC as a diagnostic tool enables the diagnosis of inflammatory and neoplastic conditions without resorting to more invasive procedures.
The early stages of tuberculous lymphadenitis have been found to present with suppuration alone. The lack of granulomas should not rule out the possibility of tuberculosis.
Metastatic malignancy is an important cause of lymphadenopathy in the elderly population.