Honey as a Cytological Fixative: A Comparative Study With 95% Alcohol

Abstract

Background Ninety-five percent (95%) ethyl alcohol (ethanol) has been used as a standard cytological fixative but it is expensive, difficult to procure, and has addictive properties. Alternate substitutes like methanol, which give similar results to ethanol, have toxic potential. Honey, a known preservative, is an eco-friendly fixative and is of great value when ethanol is unavailable and economizing on cost is necessary. The present study was done to assess and compare the fixation property and cytomorphological features of smears fixed in 20% honey in comparison to 95% ethyl alcohol and to determine whether the former can be used as an alternative cytological fixative in routine practice. Material and methods The present prospective study was done in the cytology section of the Department of Pathology for one and a half years on 300 cytological samples comprising 100 samples each of various body fluids (peritoneal, pleural, bronchoalveolar lavage, and urine), cervical smears, and fine-needle aspiration samples. The smears from all the 300 cytological samples were fixed separately in 95% ethanol and 20% unprocessed natural honey for a minimum of 15 minutes and were then stained with Papanicolaou (Pap) stain. The cytomorphological parameters of both the smears were compared based on set criteria. Relevant statistical analysis was done using the student t-test, chi-square test, and test of agreement (kappa statistics). Results A comparable and good-quality staining pattern, preservation of morphology, and crisp nuclear and cytoplasmic staining were observed between the two fixatives for all three types of samples with a strong agreement between them (kappa value varying between 0.896 and 0.942) and a p-value of <0.05. Conclusion Natural honey is a readily available and non-toxic alternative to ethanol as a cytological fixative and can be used in routine practices, especially in resource-constrained settings.

Keywords: cytological fixatives; cytomorphology; ethanol; honey; papanicolaou stain.

Figure 1. Flow chart depicting details of sample processing

FNAC: fine-needle aspiration cytology

Figure 2. Microphotograph of lymphocytic pleural effusion smears fixed in 95% alcohol (A) and 20% honey; (B); reactive mesothelial cells in pleural fluid smears fixed in 95% alcohol (C) and 20% honey (D)

Figure 3. Microphotograph of Pap-stained smears of urine showing malignant cells in smears fixed with 95% alcohol (A) and 20% honey (B); endocervical cells in smears fixed in 95% alcohol (C) and 20% honey (D)

Pap: Papanicolaou

Figure 4. Microphotograph showing atrophic changes in the cervix in smears fixed with 95% alcohol (A) and 20% honey (B); apocrine cells in breast FNAC smears fixed in 95% alcohol (C) and 20% honey (D)

FNAC: fine-needle aspiration cytology

Figure 5. Microphotograph of FNAC breast showing a phyllodes tumor in smears fixed with 95% alcohol (A) and 20% honey (B); metastatic adenocarcinomatous deposits, liver FNAC smears fixed in 95% alcohol (C) and 20% honey (D)

FNAC: fine-needle aspiration cytology

Figure 6. Microphotograph of FNAC lymph node showing NHL in smears fixed with 95% alcohol (A) and 20% honey (B); FNAC of parotid gland showing pleomorphic adenoma in smears fixed with 95% alcohol (C) and 20% honey (D)

FNAC: fine-needle aspiration cytology