Common practice issues in pulmonary cytology/small biopsy: Diagnostic pitfalls and appropriate use of immunohistochemical stains

With the increasing emphasis on early detection of lung carcinoma in clinical practice, the utilization of small biopsies including cytology specimens has become more prevalent and an integral part of the diagnostic process. While holding immense significance for patient care and decision-making, the accurate identification of lung carcinoma from these small biopsies poses challenges. There is a significant overlap in the characteristics among benign, reactive, and malignant processes. This is aggravated by the absence of distinguishing biomarkers. Preserving specimen material for additional cytogenetic and molecular testing has also gained prominence to enable targeted precision medicine. The focus of our review is directed towards understanding the morphologic attributes and potential diagnostic mimickers associated with the most frequent types of lung carcinoma observed in small biopsies. Additionally, we emphasize the importance of proper immunohistochemical staining practices to preserve tissue for further molecular testing.