Role of Special Stains in the Diagnosis of Infectious Diseases in Tissue Sections: A Retrospective Observational Study

Rezumat

Background:
Histopathological examination remains an important diagnostic modality for infectious diseases, particularly when microbiological culture or molecular testing is unavailable or inconclusive. Although routine hematoxylin and eosin (H&E) staining provides important tissue information, special histochemical stains improve the visualization and identification of microorganisms in tissue sections.

 Methodology:
This retrospective observational study included 350 tissue specimens received in the Department of Pathology, Government Medical College, Alwar, over two years. H&E sections were reviewed, followed by Ziehl–Neelsen (ZN), Periodic Acid-Schiff (PAS), Grocott Methenamine Silver (GMS), Gram, Fite-Faraco, Giemsa, and Mucicarmine stains whenever indicated. Clinicopathological details, organisms detected, and diagnostic yield were analyzed using descriptive statistics and the Chi-square test.

 Results:
The mean age of patients was 43.8 ± 17.6 years, with the majority belonging to the 41–60-year age group (38.3%). Infectious organisms were demonstrated in 232 (66.3%) specimens. Fungal infections were the most common diagnosis (35.4%), followed by tuberculosis (31.4%). PAS and GMS showed the highest positivity for fungal infections, while ZN and Ziehl-Neelsen effectively demonstrated acid-fast bacilli. Special stains significantly improved etiological diagnosis compared with H&E alone (p<0.001).

 Conclusion:
Special histochemical stains remain valuable adjuncts to routine histopathology and enhance the detection and identification of infectious organisms in tissue sections.

 Recommendation:
Appropriate special stains should be selected according to histomorphological findings and clinical suspicion, with correlation with microbiological and molecular methods whenever available.