Intraoperative frozen section diagnosis of lung specimens: An updated review

Intraoperative frozen section (FS) diagnosis is a critical step in the management of patients with pulmonary lesions, which provides guidance for surgical resection procedures. Intraoperative FS diagnosis requires a comprehensive approach that integrates clinical information, imaging findings, and histopathological evaluation. Effective communication between pathologists and surgeons is vital for achieving the best practice result. Intraoperative FS diagnosis faces new challenges in the era of new lung cancer screening strategy, changes in histological tumor classification and addition of new lung tumor entities. Below we discuss the challenges in pre-intraoperative assessment and intraoperative diagnosis of pulmonary nodules. Key considerations include clinical information and CT imaging findings. Multiple nodules require strategic sampling, focusing on the most malignant-appearing lesion. Intraoperative FS diagnosis involves recognizing growth patterns and cellular atypia that help distinction of preinvasive lesions, minimal invasive, and invasive tumor although it might be challenging. Distinguishing benign from malignant tumors is also discussed, with emphasis on histological and imaging features. Special considerations include spread through air spaces (STAS), margin assessment, lymphoproliferative disorders, infectious diseases, and benign or uncertain-behavior tumors.