Impression Cytology as a Diagnostic Tool for Ocular Surface Squamous Neoplasia: An Exploratory Case Series From a Rural Tertiary Care Center in India.

BACKGROUND

Ocular surface squamous neoplasia (OSSN) presents diagnostic challenges in resource-limited rural settings where access to histopathology is constrained. This exploratory study evaluates the feasibility and clinical utility of impression cytology (IC) as a non-invasive diagnostic approach for OSSN in a rural Indian tertiary care center.

METHODS

We conducted a retrospective analysis of seven patients with clinically suspected OSSN. IC was performed using cellulose acetate filter paper (0.22 μm pore size) applied to the lesion surface for 5-10 s. For each lesion, separate samples were collected: one fixed immediately in 95% ethanol for Hematoxylin and Eosin (H&E) staining, and one air-dried followed by methanol fixation for May-Grünwald-Giemsa (MGG) staining. Cytological assessment focused on cellular atypia, nuclear-cytoplasmic ratio, pleomorphism, and chromatin pattern. Clinical management and outcomes were correlated with IC findings.

RESULTS

IC provided adequate cellular samples in all cases, enabling cytological grading across the OSSN spectrum: mild dysplasia (3 cases), high-grade dysplasia (3 cases), and cytological features suspicious for possible invasive squamous cell carcinoma (1 case). In cases treated with topical mitomycin C (MMC) based on IC guidance, complete lesion resolution was achieved at last follow-up (ranging from 3 to 6 months) without recurrence. Histopathological confirmation was available in 3 cases (including the case suspicious for invasion) and showed complete concordance with IC findings. The procedure was well-tolerated with 100% patient compliance.

CONCLUSION

Impression cytology is a feasible, minimally invasive diagnostic tool for OSSN that can identify dysplastic changes and guide clinical management in resource-limited settings. While it cannot definitively diagnose stromal invasion and histopathological confirmation remains necessary when invasion is suspected, IC serves as a useful screening and monitoring modality in rural healthcare environments. Larger prospective studies are needed to validate these preliminary findings.