# Comparative Evaluation of Routine and Special Staining Techniques in Fine Needle Aspiration Cytology of Lymph Nodes

## TL;DR

This study compares routine and special staining techniques in diagnosing lymph node conditions using fine needle aspiration cytology, finding that special stains improve accuracy, especially for tuberculosis detection.

## Contribution

The study demonstrates that auramine-rhodamine staining is more sensitive than Ziehl-Neelsen for detecting tuberculosis in lymph node aspirates.

## Key findings

- Auramine-rhodamine staining detected acid-fast bacilli in 27.8% of tuberculosis-suspected cases, compared to 11.1% with Ziehl-Neelsen.
- Reactive lymphadenitis was the most common diagnosis (57.7%), followed by granulomatous lymphadenitis (22.1%).
- Immunocytochemistry showed CD45 positivity in 25% of malignant cases and CD15 positivity in 12.5%.

## Abstract

Background and objective: Fine needle aspiration cytology (FNAC) is a fast, inexpensive, and least invasive form of diagnosis, which is commonly used in the assessment of lymphadenopathy. In developing nations such as India, malignancies and tuberculosis (TB) are some of the most frequent causes of the enlargement of the lymph nodes. Although regular cytology stains are commonly used, they are not always sensitive to some infections and neoplastic diseases. The objectives of this research were to compare and evaluate diagnostic using routine and special staining methods in FNAC of lymph nodes.

Methods: This is an observational study conducted over 18 months in the Department of Pathology at Era's Lucknow Medical College. A total of 104 patients with lymphadenopathy who were subjected to FNAC were enrolled. Routine (hematoxylin and eosin (H&E) and Giemsa), special (Ziehl-Neelsen (ZN), auramine-rhodamine (AR), and periodic acid-Schiff (PAS)), and immunocytochemistry (ICC) (CD15 and CD45) stains were used to stain aspirates. SPSS version 18 (IBM Corp., Armonk, NY) was used to analyze the diagnostic findings by applying the Chi-square test, Cohen’s kappa, and adjusted sensitivity and specificity measures.

Findings: Reactive lymphadenitis was the most frequent cytological diagnosis, observed in 60 cases (57.7%), followed by granulomatous lymphadenitis in 23 cases (22.1%). Among the 36 cases suspected of tuberculosis on cytomorphology, auramine-rhodamine staining detected acid-fast bacilli (AFB) in 10 cases (27.8%), whereas Ziehl-Neelsen staining was positive in only four cases (11.1%). Malignancy was diagnosed in eight cases (7.7%). Immunocytochemistry revealed CD45 positivity in two of the malignant cases (25%) and CD15 positivity in one case (12.5%). Agreement between clinical suspicion and cytological diagnosis of malignancy was strong (Cohen’s kappa = 0.754).

Conclusion: FNAC used in conjunction with special stains and immunocytochemistry is much more effective in increasing diagnostic accuracy in infectious and neoplastic lymphadenopathy. Auramine-rhodamine was more sensitive than TB-Ziehl-Neelsen. This integrative methodology plays an essential role in proper and early diagnosis, particularly in resource-limited environments.