ROSE on small-cell lung carcinoma involvement of mediastinal lymph nodes: Performance evaluation at our institution

Recognition of lymph node involvement by small-cell lung carcinoma (SCLC) is challenging, especially during rapid onsite evaluation (ROSE). This distinction might carry clinical significance especially for staging and potential therapy.

Cases with ROSE of lymph nodes for assessment of involvement by SCLC between 2020 and 2024 at our institution were reviewed. Adequacy evaluation results were correlated with the final diagnosis. Smears used during ROSE from cases with diagnostic discrepancies between ROSE and final diagnosis were retrieved for additional review. Interpretation accuracy was measured, and useful features for recognizing SCLC and possible contributing factors for misrecognition were studied.

The majority of the cases show concordance between ROSE interpretation and the final review. Most discrepancies are due to under-recognition of scant SCLC cells from background lymphocytes or abundant necrosis. Rapid Papanicolaou-stained smears showed better sensitivity and specificity for recognizing SCLC cells than Diff-Quick stain during ROSE. Pathologists in practice for a longer period (>5 years) are more likely to accurately distinguish the carcinoma cells. Shorter time seems to have been spent onsite for evaluation of cases with under-recognized SCLC cells, but the association is not statistically significant.

Accurately recognizing lymph node involvement by SCLC during ROSE is important for timely diagnosis, triage, and management of cases. Several cytologic features should be utilized for accurately distinguishing SCLC cells from lymphocytes. Experience gained with practice increases diagnostic accuracy during ROSE, and rushing should be avoided. Knowledge of clinical impression and clear communication with clinicians should always be encouraged.